Trolls, what is wrong in their mind?

I got to blow off some steam, I admit it.

I went in an ARAM. I got Kalista. I'm not a Kalista player and I struggle with builds in general. Anyway, it wasn't so bad, I had fun, we won, enemy team was nice, etc. But there was this one person on my team, picking on me. I said nothing all chat. Post-game, I asked why they were so mad. They said "because you are garbage". I told them I hadn't said anything all game and asked them why they cared. They said that it was because I acted like a hotshot when I'm not. First of all, I don't know what that means, and second of all, how can someone pretend that someone else is "acting" when merely playing League of Legends.

I guess some people need to pick on others to make themselves feel better. When is tribunal going to work?

Thanks for reading.