OK OK, before anyone gets their pitchforks out, lemme explain.
I'm not saying if you watch anime, you're automatically a **** person (doing so would be saying I am too...which maybe isn't too far from the truth, to be fair!), and I'm not saying all hardcore anime fans aren't particularly nice people.
But I'd be lying if I said I didn't think that there is a large amount of anime fans I've seen (both IRL and online) who specifically aren't very nice people. And I'm not just talking about in the context of anime communities. Even when they aren't talking about anime, I always get this air of egoism from these kinds of people. Like they have a systematic need to prove their intellectual superiority at every turn, and it gets super grating.
I didn't take much notice in it online, but when I was seeing this stuff IRL, it started to hit me that there might actually be something to this.
I just wanna stress that this isn't the same as your typical argument nerds have over video games and the like. It's like a constant ego that pops up from these people in nearly everything they do.
I can only speculate, but if I had to think of an explanation, I don't think liking anime is actually a strong factor here. I think the main factors would be that a lot of these people didn't have the most fulfilling childhoods and may also be naturally introverted too, which happens to be a pretty common background for a lot of anime fans. Which can on it's own lead to some particularly negative, anti-social behavior. I do think the interest in anime plays a small part though - mainly, a common phase a lot of anime fans go through is the "ANIME IS A HIGHER FORM OF ART" phase, where they feel this need to prove to people that this isn't just a silly cartoon like those childish Western animations, but that it's an intellectually superior form of art. Most anime fans grow out of this phase, and just watch what they want and don't give a damn about what other people think, but for some, it isn't a phase. They truly want everyone to appreciate the medium in the same way they do, and this need to prove intellectual superiority manifests in the rest of their personality, extending beyond just proving that anime is great but proving that THEY'RE super amazing, intellectually superior people.
But that's enough armchair psychology for one day. Also, no, I'm not referring to or thinking of anyone in this thread.