My son plays video games all day and refuses to study, but he gets outstanding grades. How does he do it, and is it a good thing?
My cousin had the same ability, when he turned 18-19 he was screened by a psychologist and they found out he had aspergers.
Some aspergers have a very high level of intelligence, fantastic memory and incredible problem solving skills that makes schooling pretty much unnecessary. Some of them, my cousin included, has social anxieties to some degree, which prompts them to tap out of social interactions a lot of the time and turn to gaming or something else in solitude.
Maybe you should consider having your son screened.