Outside UCLA hospital they gather with their candles and their teddies, spooky lookalikes in full Thriller garb, wan teenagers wearing a single lace glove. They sway and sing I’ll Be There with sad faces to disguise the serotonin buzz from their frenzied collective mourn-in. Fans cry now for Michael Jackson, but they killed him. They always do.

I met Pete Doherty’s mother a few years back when he was at his most vulnerable, flicking between rehab and jail, just one misjudged fix from extinction. And she told me about his fans, who’d slip him gear when he was struggling to quit, tell her they went to every gig he ever performed “just in case, you know, it happens to be his last”. They loved him, they said, but really they were just tearing at his fame, wanting a piece to weave like gold thread into their own hessian lives.

Unlike his mother, fans have no investment in a star’s fate. It is win-win either way. If he lives, it means, perhaps, another album, a few more weekly mag exclusives of his loucheness, pet collection, addled decline. But if he dies, they have conspiracies to tweet about, a myth, a shrine to visit and vandalise with tea lights and kisses, like Jim Morrison’s raddled grave at Père Lachaise.

Jackson’s fans forced him into seclusion; they watched while he squandered his millions on gaudy sculptures, chimps and ferris wheels — which meant, fatally, he had to drag his frail fiftysomething frame back on tour; they sent their children for suspect sleepovers at his ranch to drink Jesus Juice; copied not pitied his self-abusive plastic surgery; didn’t petition social services when he shrouded his kids in burkas or dangled his baby from a balcony.

Any wise counsel he might have received was always mitigated by their bovine uncritical presence: how can I be crazy when my fans still love me? A fanbase, those base fans, are the reason, as much as great wealth, that Angelina Jolie feels she can demand a no-fly zone over part of Namibia while she gave birth there, or Madonna can march into Malawi and remove two of its unorphaned children without shame or concern at the outcry. Let the critics carp: I can sell out stadiums.

Fandom is the curse of our age. It has turned from admiration into obsession, respectful homage to idolatory. It is a virus to which no one seems immune. Once in New York, I passed a huge excited crowd outside a fancy hotel. What were they waiting for? Apparently Paris Hilton was inside having lunch. Foreign journalists (not so much we Brits) at Cannes Film Festival press conferences ask stars snipey questions, then rush forward at the end to demand an autograph.

I have never, even as teenager, understood fandom, can’t see the point of worshipping someone who is no more than a poster on the wall — and doesn’t even know you exist. Love their work, fancy them rotten: yes. Scream until you faint at a gig, write them loopy letters: never. Despite my children’s protestations I will never ask for an autograph. If I spy a famous person in London I look away. How embarrassing to be caught staring!

Fandom is so grossly unequal, so self-abasing. Even when you are closest to your Special One you are humiliated by his — at best — polite indifference to your pathetic, onanistic, unreturned love.

We know how the stars loathe the paparazzi, smash their lenses, call them — as Hugh Grant did this week — w**kers and losers. But what they can’t, daren’t, say is how deeply they loathe their fans — their pestering, cloying, snatching, the demand for photos amid a private dinner, the sneaky snapping with their crummy mobile cameras while a star is buying a latte, pushing his kid on a swing, their high-horse outrage when a demand is politely refused. The stars cannot complain: they have to halt their conversation and smile. These are, after all, the hands that feed them. And so Tom Cruise buys them off with a two- hour Leicester Square feeding frenzy: call my mum, now my sister, record my answering-machine message, now kiss me . . . Insatiable, terrifying.

The most troubled person I ever met was David Cassidy, the teen idol of Jackson’s era, unhinged long ago by his fans. For five years girls slept outside his house, followed him everywhere, ripped his clothing, forced him into isolation, made his life empty and lonely. And then, abruptly, when he was no longer the pretty boy du jour they deserted him. Now, two divorces later, he loathes meeting old fans, because they will say, with no regard for his feelings, how old he looks — though they are mostly portly matrons themselves — or get drunk and take a grab at him. To them, he isn’t a man, just an odd manifestation of their teenage years: they own him and they let him know it.

In interviews with the famous, the conversation inevitably drifts into how they deal with fame. The sensible ones, those fortunate to have been raised right, with an understanding of what makes them truly happy beyond fickle public acclaim, play the photo-op game, appreciate their privilege, but put a section of their lives behind a velvet rope. (Though it is my job as an interviewer to break through the velvet rope.) I suggested to Kevin Spacey, a star so secretive he signs autographs at the Old Vic from behind a wooden flap, that isn’t it the quid pro quo for wealth that fans are admitted into his private life. “I can look any fan in the eye,” he said sharply, “and say you have no right from anything from me except the best performance I can give.”

But today this isn’t enough. We demand access all areas. Through the story arcs of famous lives played out in countless celeb magazines and blogs, we make sense of our own. Their vulnerability, failings and lost loves — for all their blessings of beauty and talent — make us feel better about our own lowly woes. Fandom is imitative and passive, it makes us sweat over the ASOS website to buy a copy of a skirt we saw Jennifer Aniston wear in Heat. Fans are vampires, feeders, jackals, bores.

Long ago an audience was presented with a boy, perfect and whole, joyous as he trilled out ABC and they watched entranced as their idolatry created a lost and broken freak. Soon in their sunglasses and gloves, they will gather for his funeral brimming with mawkish self-regard, yet wishing like Ayatollah Khomeini’s own fanatics they could rip him from the coffin and tear off a relic to cherish forever. Or, better still, flog on eBay.