I would wager that there are far more immature and infantile footballers than there are really thick ones. Living slightly outside of normal society due to being good at kicking a ball around seems to lead to many of them just being big children with loads of money. Jermaine Pennant is a good example. Has the maturity of I reckon about a 13 year old, maybe 15 if I am being generous.
This. I dont think the average footballer is more unintelligent than regular people, but considering they have deidicated their lives to getting good at a sport, rather than reading, discussing and pursuing academia, they are natually going to be behind on someone who got an education instead.
Also, money and fame does something with people. If i was swimming in money like they do, i'd be even more of an arsehole