I think for the better players, those who make it to a good standard end up playing on a Saturday, when the big games are on, so it's self-defeating to be a player and a supporter. Same with those who try and "make it", it becomes like a job, but when they fail (as over 99% do) then I suppose it can be a constant reminder of failure. I've played a bit of Saturday leage down South, but not a lot of Sunday league and no school football.
In my school, it was only really the hard/ rough lads who got into the team, it was clicky as, and at school, their interest in education was inversely proportional to their interest in drugs and booze.
Most of the footy fans I know now are quite bright, but most of the better players at school, or those in the school team certainly weren't (or they were in all the bottom sets etc).