The mystery of walk-ons

I understand that if a walk-on is a Physical Education major or is planning on becoming a coach there is a direct relationship between the experience of being on a team and his career path. However, absent those two scenarios, a kid must really love the game to do everything necessary to be a walk-on in college basketball. It takes a tremendous amount of time - time that could be spent studying or working at a paying job. There is not even a realistic expectation of actually getting onto the floor during a game for a significant amount of time. So, why the expenditure of time and effort on something that would appear to yield very little reward? If it is just playing the game that is involved, then the kids could play pick-up games, or get involved in some sort of community league. A mystery to me.