Mirch- the best mentor may just be a sensible friend of his.
I would say encourage him to take some time and explore what he wants to do..
in the end time 'lost' during education more than evens out by how well you do and quickly you move up.
On topic, some kids just need maula baksh and nothing else works, I was one of those. In school it was only close monitoring and sota of my parents that got me into college, In college I did bare minimum to just get through and took me more time than usual, it was only after graduation and entering the job market that I pulled my act together.
Sounds like my eldest brother, while growing up my parents had the toughest time with him. His dictation and maths were always wrong so even if he wrote the right answer he never got marks (this was later diagnosed as dyslexia when he was in in his teens) and he just never seemed interested in studies. Till 9th grade he was continuously failing in his grades and my parents were worried so much him being the eldest son, the only thing he was interested in was working on a computer and reading comics( this was in the early 80's).
When he reached 9th grade something changed in him, not only he excelled in his board exams but he went on doing that till now. Right now he's working as the youngest CISO on wall st, speaks regularly at Gartner conferences, directed a movie and currently in process of getting his two books published.
So I guess until the kids are not ready themselves it won't happen, the parents and family should just never lose hope in them and continue encouraging them.
Everyone seems to be quite against the idea of competition but what if he is the competitive type? What are some of his skills? And what subjects is he currently studying?