Why are Professional Athletes Allowed at the Olympic Games?

That to me is one of the biggest questions.  Why are professional athletes eligible for the Olympic games?  When you turn on Gymnastics or Swimming, you hear stories of hardship.  You hear stories about how these athletes train 24/7/365 for an event that happens just once every four years.  How they have to sacrifice everything they have for a chance at Olympic glory.  After the Olympic torch is snuffed out, Michael Phelps will more than likely begin training for London.  So will Shawn Johnson, so will Nastia Luiken.  So will every Olympian that will be able to compete again.  What will the basketball and tennis players do?  The NBA players will start training for their upcoming season, and tennis players will more than likely train for the US Open if they haven't already. 

My point is this.  As an American, there was nothing better than watching the men's 4x100 meter relay in which the underdog US just barely beat the favorite French in perhaps one of the greatest realys ever in the Olympics.  In Gymnastics, could you not feel any better for the American men, who won a bronze when they weren't really in medal contention?  Yes, Michael Phelps is the favorite everytime he even gets near a pool.  But does that mean you cheer for him any less in his pursuit of perfection? 

My biggest problem definitely has to be in basketball.  These are guys who get paid millions of dollars a year.  Their faces are on SportsCenter every day, even when basketball season is out of season.  Everyone else (including Michael Phelps), is on TV for just a couple days every 4 years.

Jim Thorpe was stripped of his medals when it was discovered that he had been paid to play minor league baseball, violating amateur status.  They were later restored, but when did it change?  When did the IOC say that professional players were OK to play in the Olympics?  I don't care if you go to a tournament (as in the case with beach volleyball pair Misty May-Treanor and Kerri Walsh), win the tournament and win money.  I don't care about that.  What I care about is guys who get PAID, whether they win or not, taking spots of kids that would really appreciate it. 

Before you comment, ask yourself this question.  How would you feel if the US had no professional players, and lets say a country like Mongolia was filled with NBA stars and the US got crushed 100-40.  Wouldn't you say that's a little unfair?