It sounds even now like the account of a strange dream. It was a weekend in early autumn and I was walking with my young children through a museum devoted to woolly mammoths. As we were admiring a case of fossilized incisors, my phone began to buzz. By the time we got to the display of ancient mandibles, it was vibrating nonstop. All over the world hundreds of strangers were sending me messages on Twitter. They were very angry strangers.

“You’re a whole f***ing dumbass you miserable excuse for a journalist,” opined someone called rice lover7. Another user, uhgoodslaps, reckoned that I was a “stupid cracker”. Many of the denunciations were racial in nature, focusing on my status as a white middle-aged “crusty” or, as rice lover7 put it, a “xenophobic mayonnaise”. “Who gone die today huh?” asked @taerivia above a photograph of a young man brandishing a gun. “WHO GONE F***ING DIE TODAY.”

Like plenty of journalists, I have poked a few hornets’ nests over the years and excited the anger of touchy and sometimes sinister groups, from Japanese ultra-nationalists to Chinese Twitterbots. But nothing I have written has excited a tsunami of opprobrium like this. And this was not a pile-on about Japanese wartime atrocities or human rights in Hong Kong. The article that had caused all the upset was an interview in that morning’s Times with a South Korean boy band, seven young men known collectively as BTS.

“BTS has greatly raised national dignity by enhancing the stature of K-pop and Korean culture.”

At that time, four years ago, they were on their way to their status today as the most successful pop group in the world — in 2020 and 2021 they outsold everyone else, including Taylor Swift, Ed Sheeran and Billie Eilish. A few weeks earlier I had flown to Seoul from my home in Tokyo to immerse myself in BTS and their world. I visited an exhibition devoted to the band in a smart museum. I attended a sold-out concert at the Seoul Olympic Stadium, where for three hours the boys sang, danced and emoted for their fans.

There were repeated and dazzling costume changes — gold-braided uniforms, leather trousers, spangled tuxedos. The band were constantly in motion, flawlessly in time and on cue; the show was so lacking in rough edges that it felt more like a live pop video, created with the most advanced computer graphics rather than live performers. And a few days later I drove an hour out of the city and talked to BTS in the studio where they were working.

Many of the denunciations were racial in nature, focusing on my status as a white middle-aged “crusty” or, as rice lover7 put it, a “xenophobic mayonnaise.”

Compared with the hyperactive mannequins onstage, they were decent, reflective, and completely exhausted. They talked about the stigma in South Korean society around discussions of mental health. They spoke of the punishingly long hours imposed on them by their management agency.

“I don’t think anyone would want to date us,” Park Ji-min said. “We don’t have time to see our own families, to be honest. We don’t have a normal pattern of life. Even if we were to date, I don’t think that you could call it real dating.”

Former South Korean president Moon Jae-in poses for a photo with J-Hope, a member of BTS.

It was a remarkable and unexpected conversation — the opposite of the PR pap that I had been expecting — and it accorded with other dark stories about the world of K-pop, about the pressures imposed by powerful management companies on its very young “idols”. The life of BTS seemed to me like a formula for nervous collapse. And less than four years later, so it has transpired.

Last week, in an emotional video posted online, BTS announced that they are taking a “hiatus” after becoming “exhausted” by the relentless pressure. Their management agency insists that this is a temporary adjustment to allow the boys to record as solo musicians, but the 28 percent drop in the company’s share price suggested that many investors, at least, believe that the BTS cash cow has run out of milk.

Stories of young stars whose success turns to disillusion are almost routinely familiar. But BTS have faced unique pressures. Part of the problem is the institution of K-pop, which elevates a small number of idols out of hundreds of thousands of aspirants and takes control of every aspect of their performing careers. This is pressure enough on acts whose success is confined to South Korea.

In their global success, BTS have taken on a still greater national responsibility, as symbols and standard bearers of Korean pride. A tragically divided people, surrounded by powerful neighbors that have bullied and dominated them throughout history, many South Koreans have a strong sense of being insufficiently recognized and respected, compared with Japan and China.

Compared with the hyperactive mannequins onstage, they were decent, reflective, and completely exhausted.

“BTS has greatly raised national dignity by enhancing the stature of K-pop and Korean culture, and I am grateful in many ways,” Moon Jae-in, the country’s president at the time, told them. As his First Lady, Kim Jung-sook, added proudly, “Our generation studied English listening to pop songs, but now the global audience is learning Korean to understand BTS songs.”

Even to people with little interest in its music, the band are a leading Korean export and a strategic national asset. They have been at the center of a debate about the two years of military service that is still mandatory for all young South Korean men. There have been huge petitions by fans pleading with the government to exempt BTS — but to no avail.

And then there is the other Army — the “fandom”, as they call themselves — an acronym for the baffling phrase “Adorable Representative MC for Youth”. Having glimpsed their less adorable side, I have asked myself what it was about my article that upset so many people. The truth is, of course, that it was written not for members of Army, but for their parents, curious about the exotic craze suddenly preoccupying their children.

Maengbang Beach in Samcheok, where BTS shot the album cover for its hit single “Butter.”

You go to BTS for the music and the dancing, not the philosophy, and the band members’ public utterances — support for tolerance and self-respect; opposition to prejudice and hate speech — are as vapid and obvious as most pop star blather. At one point in the piece I poked gentle fun at Kim Nam-joon, or RM, the English-speaker of the band, who learned the language from watching episodes of Friends. “Despite the claim of my fan guide that he has an IQ of 148,” I wrote, “he gives the impression that he is channelling Joey rather than Chandler.” This, as I thought, fairly gentle tease excited many accusations of “xenophobia” from indignant teenyboppers.

No one said as much, but I suspect that I committed a greater and simpler offense. BTS are among the most famous, successful and desired young men in the world, and yet against my expectations I came away feeling sorry for them. In person, they were sad rather than sexy; knackered, not glamorous. They were the most put-upon multi-millionaires I have ever met. It must be painful, as a “fandom”, to be told that your heroes are miserable, in part because of the burden that you impose on them.

“The problem with K-pop and the whole idol system is that they don’t give you time to mature,” RM said last week in announcing the band’s hiatus. “You have to keep producing music and keep doing something. And after I get up in the morning and get makeup done there’s no time left for growth.” May BTS’s next chapter be rich in opportunities to grow and mature, for their fans as well as for them.

Richard Lloyd Parry is the Tokyo-based Asia editor for The Times of London