A few years ago, a man staged an attack on the Dutch Royal Family, killing 7 innocent bystanders and himself in the process. It shocked the nation.
Wanting to understand what had happened , I read up on people like him. I read all about howlers (fanatical fans) and hunters (dangerous "anti-fans"). I read all about how howlers never hunt and hunters never howl. It was a frightening look at the dark side of fandom.
Every celebrity has fans, no matter how insignificant their talent or how short their stay in the limelight. And among their fans will be a few howlers, it just goes with the territory. These people like all other fans just want to feel or even be close to the object of their desire, but unlike all other fans they will go to great lengths to make that happen.
If you've ever been part of any kind of fan community, you've probably met a howler or two. I've certainly met my share of slightly deranged George Michael fans. Mostly they made my skin crawl, but sometimes I was a bit jealous as well. They are really dedicated. They make friends with all the people connected with a George Michael tour, to get as much the information and help as possible. I could never do that as I'm much too self-conscious for stuff like that. But the super fans just go for it. Weird they may be, but they get results!
Howlers can be a nuisance, but they're not dangerous. Hunters are quite another matter. The man who shot John Lennon for instance is considered a celebrity-seeking hunter. They can be very dangerous. The threat of a hunter is probably what keeps the security people of big stars awake at night.
I don't understand hunters, but then I'm reasonably sane. There are lots of people in the public eye that I've hated for all sorts of silly reasons. Never, ever did I think it was necessary to let them know this, let alone 'do something about it'. That's what your imagination is for!