Ego but mostly lack of communication and information. Sometimes players would just think that they're team got their back but they don't. Also you gotta realize that they don't have the same info as we viewers do, they don't know where enemies exact location are so sometimes they panic.
because you start feelin like the best player in the server..
then you get one-tapped as you peek and by then, you have successfully thrown the round for your team!
Discord