I've been playing more games online lately and I've found two things:
1. Lots of really nice people. I just spent an hour playing a game with a man in Brazil and we used Google translate to chat and teach each other our respective languages while we played.
2. It's actually really easy to get angry. Like, I'm an adult and even I have to be like "hey it's a game chill" to myself - I've never blown up at anyone but... holy shit, it's kind of insane how bad some people are lol. And it's frustrating. Like go to the objective, the game is literally blaring that you should go there, why are you going elsewhere????? over and over again.
With regards to gaming it's just a sort of "worst case" for human collaboration. It's fast paced, high pressure, and communication is both the most important part and also by far the hardest. It is absolutely no surprise to me, whatsoever, that anyone who plays a lot of video games might get angry easily.
Also, as someone who grew up very "on the internet", there's a lot of bitter and angry people out there. They're kind of relatable in a way. Like the whole "I want to fucking die" meme is sort of a meme but also sort of real and relatable, but when you smash that into your brain every day it stops being a meme, and I think that's the case with most irony poisoned internet discussions.