Personally, I see the whole leaving your college team early to be prepared for the pros thing a morally gray area. Certainly you made a commitment to your university, and they are "paying" you in the form of a scholarship. At the same time I think it's almost impossible for most of us to fathom the decisions these kids are making. Many of them come from impoverished homes where their families are rubbing two sticks together just to get by. They have this opportunity to make enough money to take care of their families for the rest of their lives, and they don't want to screw that up.
It's not as simple as saying "they reneged on a commitment they made to the university and their teammates." Honestly, most of their teammates, having come from a similar background, probably understand and support them. At the end of the day you have to do what's best for you and to take care of your family. If walking away from a college sport part way through the season guarantees you won't get hurt and spoil the opportunity to ensure your family never needs to worry about going hungry again would you do it? It would certainly be a tough decision.