Having dealt with professional athletes in three non-cycling sports over the years, my experience has been universal. The higher up they are on the totem pole, the more decent and unassuming they are. On the other hand, the high end amatuers who are knocking on the door tend to be the rudist and most arrogant. Hard to say if the big time pros are nice because they've made it, or made it because they're nice. I tend to think 60/40, towards the latter.

In terms of cycling, I've ridden with a few high end amatuers, and if they weren't good enough to be low end pros, I don't want to even think what the big boys ride like!