Not being a pro athlete I don't know the pain that goes into working the body to perform to the kind of levels it takes. What that does and the ego that drives a player to be in that elite position is very foriegn.
Coming form a "middle class" environment growing up vs. priviledged vs "challanged" would have a big effect. Grant Hills parents did very well and here is a kid who stayed 4 years a Duke, got a few NCAA chips and made 100mil plus. He never chased a ring putting his family above by keeping it as stable as he could. Iverson on the other hand came from poverty and blew his money.
I think some players that have balance in their lives consider it a profession and have to work damn hard. The few that transcend the sport and can dictate circumstances like Lebron have a legacy to fulfil.
I think the answer lies in each circumstance/player and their back ground.