Why do people give up so easily???

I feel like people just give up half way through a game because they are not doing good. But in my opinion just because you are behind, it doesn't mean that you should just throw in the towel after one bad play. People tend to say "gg" after 10-15 minutes in game if they are not doing good which i don't know why. I have been playing league since season 2 but i never really ranked much until this season and i find this as a repeating pattern, people just go in game happy then give in to rage or "salt". As a top laner sure it feels a little off being unable to help the team asap but i still try to catch up as soon as i can to help others. I want to know the community's point of view. Why does people give in so easily in a game.