Most people who stop playing, stop because they stuck in elo.
people who dont have fun anymore stop, because of bs reasons most of the time. I have so many friends, quitting games after games, because they have no discipline and have no goals or can not achieve certain goals. Most gamers are just pure casual. It is 100% okay to be casual or to play games casually, but there are so many tryhard-rage-casual-gamers(who think they actually try).
These types will leave every game and will play solo games like pubg and fortnite.
edit: why pubg and fortnite? “because team is holding me back” -tryhard-casual-gamer.