Look at the big picture. For instance pro players are only guaranteed money under certain circumstances. I know a few guys can't even own/ride a motorcycle, bicycle, anything because if they get hurt outside the game or can't play they are SCREWED!!!
For some it's also not why, but why not? They have the money and the means to build/own it, who is stopping them from doing it? They can drive it, just because they aren't going to race it doesn't mean anything. Heck, look at all the people that do car shows. I can't stand fixing up something to LOOK nice but never run, race, or even drive it. That's far worse in my opinion but again different strokes for different folks. Some people just don't like going fast....