Its because a good esports career lasts 4 years tops. 10k sounds like a lot, but after your career, what do you do? You don't have a diploma, unless you were an IGL you're probably not gonna be able to coach a team. IF you manage to join a T1 team, you need to hope you play well AND attract a substantial fanbase so you can start content creation or something else in that trend or you're gonna end up broke on the streets.