Like it or not, they ARE star athletes; they play at the highest level. I'm not saying they ARE stars...but there are people who believe so, that's why they're playing.
Here, let me give you more examples, this time with your stars...
Marcus Camby.
Shaq's shoes. In K-Mart.
Tony Romo.
Chris Paul.
Steve Nash.
Dirk Nowitzki.
There's athlete's who aren't nearly as good who have more endorsements. Wonder why...