A funny thing happened to Jeffrey Sachs on his way to becoming president of the United States. The Columbia University economist with the cocksure demeanor and the Kennedy-esque head of hair who once had the ear of U.N. secretary-general Kofi Annan, the financial backing of George Soros, the friendship of Bono and Angelina Jolie, and a plan for ending global poverty has become, instead, something between a ghost and a … well, if not a laughingstock, exactly, then a sort of impeccably educated Thanksgiving uncle.

Consider that in one of his increasingly rare appearances in the mainstream media—Bloomberg Television, last October—Sachs, brought on to discuss the invasion of Ukraine, surprised host Tom Keene by stating as fact that it was the U.S. and not, as first reported, Russia that had, in 2022, sabotaged the Nord Stream pipelines, those undersea conveyors of natural gas to Central Europe, presumably as a sub-rosa way of punishing Vladimir Putin beyond the announced sanctions. (Sachs’s basic line about Ukraine is that we ought not be overly hard on Putin, because Russian history and World War III.)

“Jeff, we’ve got to stop there,” a flustered Keene said. “What evidence do you have of that?” The effectiveness of Sachs’s response can be inferred from a headline in the next day’s New York Post: Columbia Professor Jeffrey Sachs Yanked Off Air.

Sachs’s classy pedigree seems to both inspire and lend credibility to conspiracy theorists and shoot-from-the-hip commentators like Tucker “Just Asking Questions” Carlson. The economist’s unsubstantiated remarks on Bloomberg were repeated and enhanced last week in a Substack blog post written by the once-respected reporter Seymour Hersh, who hinged his story of American connivance and deep-sea derring-do on a single unnamed source. Needless to say, the U.S. government, and independent security experts, called the story out as being “utterly false” and a P.R. gift to the Russian government.

Nor was the Nord Stream business the only time lately that Sachs has pulled on the tinfoil hat and led the charge of the kook brigade. As the chair of the prestigious medical journal The Lancet’s COVID-19 Commission, Sachs issued a report last year that was highly critical of the international response to the pandemic in terms of costly delays and inadequate funding—but not especially controversial until it ventured into the area of the virus’s origins.

Most physicians and immunologists have maintained from the start that, while nobody knows for certain how the bat-borne virus first entered the wider world, the most likely scenario by far was that it came from a “wet market” in Wuhan, China. Sachs’s Lancet report acknowledged the need for further study but seemed to lean toward the possibility that the coronavirus originated in a Chinese-government laboratory, also in Wuhan, that happened to be doing research on similar diseases.

That is hardly a cockamamie theory; many observers are inclined to think the Wuhan connection is just too much of a coincidence to summarily dismiss, and that the coronavirus might have accidentally hitched a ride out on somebody’s skin, hair, or clothing. But Sachs couldn’t leave it at that and await the results of an investigation.

Instead, he started what sounded like a one-man game of telephone, changing his story each time he repeated it, going quickly from “It was possible” to “It was odds-on” there had been a lab leak—and that Dr. Anthony Fauci, the former chief medical adviser to the president, and many other scientists were lying about it. And why were they lying? Because, Sachs said, over howls of protest from the alleged fabricators, they had been involved in secret “gain-of-function” research meant to strengthen the virus so it could be better used in bio-defense.

And where did he float this theory—which, if you were to follow to its logical conclusion, means that the U.S. and China were working together to turn the coronavirus into a weapon? Not in The Lancet, certainly, and not on Bloomberg, CNN, MSNBC, or even Fox News, where his presence these days would not be all that astounding. No, Sachs picked his most bizarre fights with Fauci on a homely podcast hosted by the anti-vax quack Robert F. Kennedy Jr.

What’s going on here? Is something eating away at the considerable brain of the man The New York Times once called “probably the most important economist in the world”? An A.I. chatbot could not engineer more obnoxious-sounding beliefs than Sachs has expressed on the Ukraine conflict, even as Russian missiles slam into apartment houses in Kharkiv—namely that “the West” is responsible for provoking Russia’s violent invasion (just as it was in the now largely forgotten Ukraine offensive of 2014) and that President Volodymyr Zelensky’s proposed peace terms are “nonsense.”

As one of his academic peers told me, “I used to respect Sachs even if I disagreed with him, but now it’s just weird to watch him justify naked aggression.”

There is also the matter of the strange venues where Sachs is spouting this stuff. In addition to R.F.K. Jr.’s anti-vax-fest, he has popped up lately on a podcast run by a stand-up comic and conspiracy theorist named Jimmy Dore and a YouTube show hosted by former Democratic congresswoman turned right-wing firebrand Tulsi Gabbard—and more disturbingly has made multiple appearances on Chinese state TV and a Russian talk show overseen by the thuggish propagandist Vladimir Solovyov, who has called for a total leveling of Ukraine and further Russian incursions into Europe.

Is it any wonder that MSNBC’s Rachel Maddow and CNN’s Anderson Cooper look elsewhere for good talking heads, that Sachs’s former Harvard classmate the public-relations magnate Richard Edelman has criticized him publicly for his “unbelievable” parroting of Russia’s disinformation campaign—or that The Wall Street Journal recently put Sachs first on a list of “establishment figures” it called “Putin’s American cheerleaders”?

An A.I. chatbot could not engineer more obnoxious-sounding beliefs than Sachs has expressed on the Ukraine conflict.

In an e-mail response to questions I sent him, Sachs sounded nonplussed. His opinions were still drawing attention from mainstream outlets, he insisted, citing the Bloomberg appearance, “until they quickly took me off the air” (and using a smiley-face emoji to punctuate his point). The problem was not with him, he suggested, but with “the failure of the mainstream media to treat these issues—origins of the war, origins of the virus, cause of Nord Stream and several others—with sufficient interest, curiosity, objectivity and transparency.”

As for what I saw as odd outlets for his thoughts, “I believe in keeping open channels across a wide range of interlocutors. One learns more, hears different points of view, and also conveys ideas that reach other people.” In other words, nothing to see here, Mr. Reporter.

A good friend of Sachs’s who’d spent time with him lately, University of Chicago economist Chris Blattman, confirmed the attitude is genuine. “He remains the same old Jeff,” Blattman told me, and even from a distance that seems true. Sachs still has the self-assured mien, the Ivy League pompadour, and a residence in the multi-million-dollar Manhattan town house with which Columbia tempted him from Harvard in 2002.

But superficialities can be deceiving, and in fact his circumstances have changed dramatically from the days when he was saving the economies of Bolivia and Poland and boldly proposing to end world hunger. By not noticing the changes in his world, Sachs may be, as some other observers have noted, giving us another sign that he is losing touch.

“It’s a real comedown for a man who once advised major world leaders,” says the writer Nina Munk, who in 2013 published The Idealist: Jeffrey Sachs and the Quest to End Poverty, about Sachs’s work on the Millennium Villages Project in Africa. “Instead of meeting with President Biden, he now meets with Viktor Orbán.” Munk’s reference was to a highly questionable pilgrimage Sachs made to the far-right Hungarian prime minister last December.

Sachs had met Orbán in Budapest to discuss the need for an immediate cease-fire in Ukraine, a tactic that likely would wind up rewarding Putin for his violent aggression with vast territorial gains. In one of his e-mails to me, Sachs wrote, “[PM Orbán] offered many very, very astute observations. He and I also speak with many of the same leaders, so it was very helpful to compare perspectives.”

But Thorsten Benner, a former student of Sachs’s and a co-founder of the D.C. think tank Global Public Policy Institute, could only shake his head at what at best seems like Sachs’s severe cluelessness. In a tweet, Benner said he regretted witnessing the “sad and tragic self-destruction of a professor I once respected when I took a class with him.”

“The Smartest Boy in the Room”

Sachs grew up in Oak Park, Michigan, the son of an esteemed labor lawyer. Little Jeffrey was a precocious golden child who aced every exam, handed in papers that were four times as long as the teacher requested, and graduated summa cum laude from Harvard in 1976. “He has always been the smartest boy in the room,” says Munk, and if you disagreed with him, he would cut you to pieces using facts, charts, and a seemingly ever simmering anger.

Three years after he got his Ph.D. in economics from Harvard, the school made him a tenured professor. As an avowed capitalist who also believed that rich countries should bail out their poorer cousins, Sachs faced a seemingly limitless—or, at the very least, a Jimmy Dore–less—future.

Sachs’s first big non-academic break came in Bolivia, where at the age of 30 he went to work for President Victor Paz Estenssoro, doing emergency surgery on an economy that, with an inflation rate of 24,000 percent, was in total chaos. Sachs prescribed a program of so-called economic shock therapy—a fast and total transition from a state-controlled market to a free one.

Many Bolivians lost their jobs in the process, but inflation dropped to about 15 percent, and Sachs was hailed as a hero. This led, five years later, to a gig in Poland, then trying desperately to transition from Communism. Once again, shock therapy worked well enough, and Sachs found himself intoxicated, as Munk says, by the chance to change world history. When the then Russian president, Boris Yeltsin, asked him to help out at the end of the Soviet era, Sachs didn’t hesitate.

In hindsight, he really should have. Sachs’s work in Russia, though modeled generally on his Polish prescriptions, ended in disaster—between 1989 and 1999 the country’s G.D.P. dropped by more than half. Essentially, Russia proved too complex and too corrupt for Sachs to handle.

Sachs, as noted, does not suffer criticism gracefully. One fellow scholar told me Sachs “frequently goes apeshit” when disagreed with and has threatened to sue people who have debated with him. When Munk pressed him on the critiques of his work, he stormed out of the room. But not even the failure in Russia could slow his career momentum—and, as things would turn out, his downward trajectory.

If you disagreed with him, he would cut you to pieces using facts, charts, and a seemingly ever simmering anger.

In 2005, Sachs published The End of Poverty: Economic Possibilities for Our Time. With a foreword by Bono, the book became a best-seller and, even more than the earlier MTV series, The Diary of Angelina Jolie and Dr. Jeffrey Sachs in Africa, made Sachs a star. The End of Poverty offered an attractive premise—that global poverty could be eradicated by 2025 if well-off nations spent between $135 million and $195 million per year on things like improved seed, fertilizer, and insecticide-treated bed nets. But many reviewers pointed out that, attractive packaging aside, there was nothing new in its pages and that none of the oft-tried solutions that Sachs was proposing had ever worked.

Sachs’s plan was summed up by David Frum, the former speechwriter to George W. Bush, in an e-mail: “‘These ideas may have failed before, but that was because they were not being run by ME.’”

In fact, Sachs’s efforts notwithstanding, the Millennium Villages Project, under the auspices of Columbia’s Earth Institute and the United Nations and with cash infusions from Soros, failed decisively.

Maybe the best way to see Sachs is as someone who’s been a long time between hits and is feeling resentful about it. On his personal Web site, he refers to himself with typical modesty as “a world-renowned economics professor, best-selling author, innovative educator, and global leader in sustainable development.”

But while he still writes books, The New York Times has stopped reviewing them. The European Union, where he serves as a special adviser to foreign-policy chief Josep Borrell, quickly distanced itself from Sachs after he advanced his theory about a coronavirus lab leak, noting that he was merely an “external, unpaid adviser.” The Sachs-for-president Web site, it almost goes without saying, has been shuttered longer than Radio Shack.

Even worse, though, may be the way that, these days, he’s being largely ignored. “That must be devastating for him,” Munk says. For what it’s worth, neither Angelina Jolie nor Bono could find time to say a word about Sachs for this piece. For the smartest boy in the room, that’s got to hurt.

Charles Leerhsen is a former executive editor for Sports Illustrated and the author of several books, including Ty Cobb: A Terrible Beauty. His latest book, Down and Out in Paradise: The Life of Anthony Bourdain, was published last year by Simon & Schuster