I get your point... I'm also into cool-headed and smart mcs... at the same time... him being hot tempered makes him more relatable to me as a gamer... I don't think there's much for him to think about besides avoiding the guys that betrayed him... and he's slowly rethinking situations with them that show they weren't as tight as he thought they were... and him refusing thunder girl's offer over them didn't make them any happy or grateful.
About him hating on her instead of them tho... it's explained better on the novel... he does hate them... but she didn't just incite them to betray him, she paid people to kill him again and again until he hit level 0 and made it impossible for him to play... and to basically loose his job... that's why he hates her more than the betrayers...
But things are more complicated than that and there's people manipulating things from the shadows... but it may really not be your tase since is a bit more on the comedy than serious action...

I know this game is basically his job but I prefer if the MC is calm and mature. Like chill. Being betrayed is painful, I get it. But I feel like he's a bit petty. I thought that being betrayed makes one rethink a lot and planning a lot. Because that what I did. The MC now is as if trying to cope with the painful facts and hating/having a beef with that blonde dude for no reason. Hate on that thunder girl whatever is understandable though.
I'm also surprised at how he hate the girl instead of the guys that stabbed him before.