15K Games = 1000 Elo Wth is wrong with you people?

Also, some people simply don’t have the mental capacity for calculating lines and remembering principles.
Of course, I’m not one to talk because I have not played that many games and don’t know my “real” rating yet.
How on earth are there so many people with like 15K Games and 1000 Elo?
What is the reason behind that?