Why is it that most of the league community has to suffer for other people's decisions.

I have been playing league for over a year now. In this time, I have learned a lot but, the biggest thing I have learned is how many "NOT NICE" players there are in this game. I try and play this game as a recreational thing, I spend a good amount of money in skins and champions. The most common thing that happens to me, is that I get in this rage for other people's selfish and thoughtless decision makings. No one in lower elo ever considers the team composition and just picks whoever they want. I either want to leave or when I do play, I tend to do my best to carry. Even then people keep ruining my experience with this game. I do not want to quit league. I almost feel like I have no choice. Please help me. Please I am tired of raging or having to calm myself down for other people's way of acting.