I have been around gaming for way over a decade and I speak from a lot of personal experience when I say that gaming can cause a lot of grief, even suffering at times. This will not be a long rant on the topic, I just finished typing up a criticism of feminism so I'm a bit exhausted :(
A very common phenomenon:
Berating yourself, playing subpar but unable to quit.
This is a vicious cycle that all players go through sometimes. Unfortunately, a lot of players get stuck in this behavior. This player or person I should say, has a defined mental track of what a gaming session will bring, and, consciously or subsonsciously has a pretty good image of what it will look and feel like. When these unhealty expectations aren't met, he or she get frustrated. The typical reaction now is to turn inwards and berate yourself. "Come on ffs, this is not anywhere near my top performance". Some players turn outwardly and complain about cheaters. It's a different problem but with the same basis.
What people fail to realize, and this happens all the time, is that no player has just one level of performance. Some of the top players get pretty close I guess, but noone is stoic enough to be completely vaccinated agaisnt these problems.
And I'm not just talking about the obvious trivialities. Everyone knows that sleep deprevation, hangover, illness etc will have a considerable impact on performance. I'm talking about deep emotional movements. Sometimes you won't be able to tell why you feel great or sort of lowish. It could be in part due to a lack of self awareness but I doubt anyone is conscious enough to now the exact origin of their current mental state at all times.
Therefore it is important to develop some kind of framework in how to deal with this. It's not an easy answer solution. Start with the more obvious things. If you start raging in the chat, leave immidiately. Finish the game at hand but if it gets really painful, kindly excuse yourself and leave.
It might sound cliché but play when it's fun and quit when it's not. Clichés are good in the sense that they are often true but you usually learn the truth by experience then realize the cliché was spot on all the time. Therefore it's not constructive one bit to just spout banalities such as this one.
See you in the arena :)