Why do trolls troll?

I have to wonder sometimes, what is the point? If you are going to troll, why not go do a custom game, or a co-op vs bots game, why do it in ranked of all places?

I have never gotten 3 trolls in one game on one team before until last game, and it just made me honestly wonder, what is the point?

First pick insta locks fizz jungle, then proceeds to ask how to jungle fizz, I dodge. I wait out and somehow...after waiting out my dodge penalty I SOMEHOW got him again, first pick. Same shtick. First pick Fizz jungle, asks how to Fizz. Starts the game 0/8, gets a kill cause they dove fountain.

Our adc decided it was better to not buy items the entire game, and her duo partner just followed our mid around spamming taunt and intentionally feeding as best he could.

What's the point? It isn't like it was Bronze 5, so how do these people even get out of Bronze, and why bother if you are gonna do this garbage? How are these people not banned by now, cause they ruin games a lot more than some angry 12 year old talking about my mom, or wishing cancer on me.

I can't mute trolling, Riot.