At the stroke of noon on January 20, the QAnon mass delusion of a vast pedophile conspiracy populated by Democrats, coastal elites, and organs of the deep state, and whose exposure would prevent the ascension of Joe Biden to the presidency, smashed into the brick wall of reality, leaving its adherents disoriented and angry.

Since at least the invention of the printing press, in the 15th century, and likely before, contagious conspiracy theories have swept through societies, and their births, exponential growth, and anticlimactic collapses have followed a characteristic historical trajectory.

For starters, QAnon’s bizarre obsession with widespread pedophilia is an age-old trope. The infamous anti-Semitic blood libel—that Jews murdered Christian children to supply blood for baking into Passover matzos—circulated widely throughout Europe for most of the second millennium. The 1980s and 1990s brought a moral panic featuring fraudulent allegations of satanic ritual murders and pornography rings that preyed on toddlers at day-care centers, whose numbers had swollen as a result of the era’s dramatic increase in women’s employment outside the home. Multiple high-profile, bogus prosecutions attracted the testimony of Satanism “experts” and ruined the lives of many innocent and unlucky day-care operators.

One such expert was Ted Gunderson, a former F.B.I. official who had worked on cases including the suicide of Marilyn Monroe and the assassination of John F. Kennedy; headed the bureau’s Los Angeles, Memphis, and Dallas offices; and nearly became its director. After his retirement, he asserted that each year 4,000 American children were kidnapped from maternity wards, ritually murdered in satanic rituals, and their remains disposed of in mobile crematoria.

Solving for Q

Beginning around 2017, the right-wing conspiracy movement QAnon bruited the existence of a cabal of satanic, cannibalistic pedophiles that aimed to defeat Donald Trump. The president would expose this evil plot just before the election, arrest its principals, and triumph at the polls. By 2020, more than half of Republican voters believed at least partially in this fantastical narrative, a stat which played out at the ballot box when voters sent two of QAnon’s supporters, Lauren Boebert and Marjorie Taylor Greene, to Congress.

None of these doomsday events, of course, transpired.

On Inauguration Day, the QAnon mass delusion of a vast pedophile conspiracy smashed into the brick wall of reality.

The fate of other mass-delusional movements offers some insight into QAnon’s future. Perhaps the most relevant episode played out nearly two centuries ago, when hundreds of thousands of Americans, led by a mild-mannered preacher named William Miller, convinced themselves that the world would end on October 22, 1844—a date that Miller and his followers had arrived at with a mind-numbing series of calculations based on Scripture—but the lives of the truest of Protestant adherents would be spared, and that they would be raptured into heaven before the fiery end.

The inevitable collapse of that narrative played out in waves, and its fallout has echoed down to nearly the present day. The initial 1844 disconfirmation was known to religious historians as the Great Disappointment. On that day, the righteous weren’t raptured up to heaven and the world didn’t end, all of which resulted in an immobilizing depression among the faithful. Most quietly fell away from the sect. Miller died in disgrace and disillusionment several years later, while his main lieutenant, Joshua Himes, reverted back to his childhood Episcopalian faith. A large number of believers evolved into today’s peaceable Seventh-day Adventists, while a smaller number formed fanatical splinters that held, among other things, that although Jesus had not returned, he had shut the door to salvation on all but “the Elect”—that is, themselves.

In the 1930s, a small number of Seventh-day Adventists were mesmerized by a salesman with a third-grade education named Victor Houteff, the recipient of a divine end-times prophecy that involved his leading 144,000 believers—the Davidian Seventh-day Adventists—safely through the inferno described in the Book of Revelation. After Houteff’s 1955 death, his widow, Florence, predicted “the End” for April 22, 1959, and, as in 1844, the inevitable anticlimax yielded yet another splintering into sects.

One of the fragments, the Branch Davidians, fell under the leadership of a former Houteff follower named Ben Roden. When he died, in 1978, the group’s leadership passed to his widow, Lois, who took up with a handsome young acolyte named Vernon Howell. Howell would later become known to the world as David Koresh.

Even Koresh’s fiery demise, at the Davidian compound in Waco, Texas, along with more than 70 of his followers on April 19, 1993, at the hands of F.B.I. agents completely ignorant of his apocalyptic belief system—fictionalized for the television series Waco—did not end the Branch Davidian tragedy. A gun-rights activist named Timothy McVeigh exacted vengeance for the deaths of Koresh and his adherents on the conflagration’s two-year anniversary, with the bombing of the Alfred P. Murrah Federal Building, in Oklahoma City, killing at least 168 people, including many children.

A large number of believers evolved into today’s peaceable Seventh-day Adventists, while a smaller number formed fanatical splinters that held that Jesus had shut the door to salvation on all but “the Elect”—that is, themselves.

When, in the 1950s, a flying-saucer cult led by a Chicagoan named Dorothy Martin met a similar wall of disproof, social psychologist Leon Festinger was present to observe the firsthand effects on her believers, which he chronicled in his book When Prophecy Fails. Before the saucer’s no-show, the group kept a low profile; afterward, they began to aggressively proselytize. In Festinger’s words, “If more and more people can be persuaded that the system of belief is correct, then clearly it must, after all, be correct.”

Both the 1844 and 1959 Adventist disappointments saw most of their true believers fall away, with a small minority of diehards forming fanatical splinter groups. Likewise did the no-show of Dorothy Martin’s flying saucers impel some of her adherents to double down on their delusion.

The same seems likely to occur with the shattering of the QAnon myth, on January 20. Already, the fracturing has begun—“It’s over,” wrote one chat-room inhabitant, while another observed, “Wake up, we’ve been had.”

The nation should not, however, be surprised if a small minority of QAnon believers gets recruited by other extremist groups or, like Festinger’s subjects and the Adventist Disappointed, double down on the QAnon narrative, and with similarly catastrophic results.

William J. Bernstein is a financial theorist and the author of numerous books, including The Birth of Plenty and A Splendid Exchange. His new book, The Delusions of Crowds: Why People Go Mad in Groups, is out now from Atlantic Monthly Press