Actually, I think coaching at the College ranks is MORE stressful than at the professional level. This is one of the reasons I think Urban will leave Florida to go to the NFL. Think about it....
College coaches have a 24/7, 360 day job. They have boosters to please, kids to mentor, recruits to swoon, academics to monitor and so on. (all of this is over and above a coaches job description in the NFL). At a large, college football institution, there is more pressure than on any pro-football team.
So the reason college coaches can't win in the NFL is because it is easier and less stressful than college. OK