dont underestimate ur mind bro. many things u learned in school, even if it was like 5th grade or sth like that, is still in ur brain. like small shit as pythagoras, grammar or even some different language words. of course, there are many things, that u wont need in ur life, but studying in school or university keeps ur mind working. dont be a 9 to 5 worker, who comes home and starts watching tv. thats no progession.