I want to say as well about games - JKR wrote well about fandoms in Ink Black Heart, but there's a lot more that could be said. I'm interested in how some fandoms are notoriously toxic and some very much aren't. A lot of that probably has to do with the demographics.
Great point, though, about gaming being more immersive, the Main Character syndrome, the repetition, the dopamine hits. I'm not a gamer and don't know the tribes, but even from my very superficial knowledge, it's hard to think of a TV or movie fandom that's quite as deranged as the Sonic fandom.