I know some:
* "nerds", "geeks" -- obsessed fans, although they also cover other groups, such as fans of a science fiction TV show or a movie (like Star Wars)
* "cancer" -- for making sites unappealing
* "cringe" -- especially if they do anything embarrassing to worsen themselves.
The "weirdos" that you describe think that doing so entertains them, and sometimes show off their interests (albeit to others' disgust) to show how proud they are to be part of their clubs. While most of them keep it as a private hobby between themselves and their friends, those who spend too much on making those hobbies a lifestyle want to show how much they love those things.
I personally think that "cosplayers" are the least unacceptable of the "weirdos" that you listed, especially if they represent historical characters or military personnel.
Spent a lot of time surfing the Internet about those groups, especially in "cringe" websites -- in fact, I'm considering writing a novel about these groups as dystopias or barbarians.
Perhaps some interests I recommend to replace include: zoology and mythology for furries, cavalry combat and horse history for bronies, historical clothing for cosplayers, Japanese history and literature for weeaboos, survivalism for Minecrafters, astronomy for Star Wars fans, and mining for Undertalers.