I disagree with it being a streamer thing. Not all streamers are like this. I think it’s more of a “streamer whose fame is partially due to how confident they sound” kind of thing. There have been situations where streamers became mad popular just because of how confident and cool they sounded, probably because the viewers also wanted to become confident and cool, even if those same streamers later ended up becoming hated by almost everyone after a few months. They try to look cool by pretending that they know what they’re talking about all the time. To back down of an opinion or judgement would destroy that façade, so streamers of this kind keep making shit up when they don’t understand something, and keep doubling down on everything they’ve ever said. The viewers either quit watching because they realize what’s going on, or become more accustomed to such toxic behaviour, maybe even deeming it acceptable. I think that’s why the audiences of these streamers also end up being kind of toxic. They start treating the streamers as one of the only sources of truth in the world, and everything else as wrong, just because the streamers sound like they really know what they’re talking about. And some of them might even acquire the same behaviour.

I think this is how it works, but I might be wrong. I’m no specialist.