Not sure how good of an example good will hunting is or if the author has seen that film - at least half of the movie and basically every supporting character is constantly telling him he can do better. It's one of the central themes!
There are also only certain ways each character can tell him those things without him shooting them down and shutting them out. Chuckie is a lot more free to talk to him about where he’s coming from and a lot more free to be blunt than his new math mentor. If we over-apply logic to human relationships and human experience without consideration for the depth and breadth of those in people’s lives, then we’re not actually being that logical in the end.