So they can say, "I bowled against the best in the U.S. Open." That would be my guess.
If that tournament was in my backyard, and I had $500, I would probably enter it too. Then you guys could track my name as I brought up the rear end of the tournament -- and I wouldn't care a bit. To just be there, playing the sport I love against the best in the world, I'd consider it an honor.
Jess