[flounders]

That's definitely one aspect to it. When I played CS:GO briefly, some of the players are just down right toxic. I don't know if it is because they deliberately want to hurt people or they just think it's perfectly fine kidding around like that, but I just stopped playing. Other games have that element to them too, but CS:GO just seemed to have a lot more of it.

[krageon]

I think you'll find almost every community of a competitive game eventually turns into a mostly toxic one. I don't really understand why (it seems a little reductionist to say that most people are toxic and therefore as a community grows most of it will tend towards being toxic), but I keep seeing it no matter what kind of game it is (RTS, MOBA, RPG, etc)

[nuclx]

They're dissatisfied with their performance measured by the time they put in. In turn team mates are blamed for hindering their progress in the ranking system.

[wolfgke]

I would even tend to generalize: The strong competitiveness of the game (or other places that are very competitive) is literally an incubator to make people very toxic towards each other.