How can a normal person not get pissed off at team mates?

Easily.

Getting pissed off at teammates is allowed. Flaming them or griefing your team is not. Just express your anger elsewhere, man. Scream at your monitor or something.

Do not try to control your anger at your team. That's impossible.

Instead, only try to realize the truth.

There is no team.

Then you'll see that it is not the team that's bad, it is only the game.

Why would I? Why wouldn't I focus on what I can control? Why would I waste time getting upset at someone for performing poorly in a video game?

There's pissed off and being a child. You have every right to be mad that someone isn't playing well in a game where you get punished for someone else not playing well. On the other hand, the blame game is used pretty darn often by people who are doing just as poorly.

The secret is to not give a shit. The instant you care more about the game than your teammates is when things run the risk of going horribly toxic. You will get those ranked matches where that one jackass decides to first time pick TF mid into a counter while trying to also teach his freshly lv 30 buddy how to play. In ranked. Also, if someone using slurs and such take a screen shot and paste it into MS Paint. Makes a good reminder 20 min later to report at the match before you go next. The "A player has been punished" notification is extreamly cathartic...

For what helps for me personally is to verbally vent frustration by just saying it at my screen, instead of actually typing it out. Apart from that music can help a lot too.

You mute them or laugh at the things they say before muting them before it gets too late? Don't feel invested or attacked when someone says things you don't agree with. Or even better yell at the screen to vent instead of typing it in chat

i only get mad at my teammates if they all seem to exist in a parallel universe. example that just happened 15min ago. my amumu, i ping my ult is on 27 sec cooldown, i see the enemy cass approach from a weird angle, i turn away. 1 sec later she flashes over the wall and ult stuns all other 4 of my teammates besides me. 3 of my team "amumu you fucking r%%%%% either press r or dont engage".

me being a meele and the only one surviving the enemy cass flash ulting us "engaged".

thats the only time im losing it.

Realize they aren’t (most likely anyway) trying to slight you. Everyone has games where they feed, where they shit the bed, where they just suck ass and most are doing it intentionally.

you just have to legit not give a fuk.

its a game. it will be over. move on to the next. if someone did something you deem to break TOS then report them.

dont let it get to you

https://boards.na.leagueoflegends.com/en/c/gameplay-balance/h9Bt91mt-state-of-the-game

my post giving some idea so people like you and me who do get mad, don't get punish so harshly because we have back to back game were we are trying, and our teammates are passively inting, and we get in trouble, and they carry on.