Greed is a powerful factor.
If you had a board offshore and you (mistakenly) thought you were untouchable, would you turn down big bucks when some dude from China came calling and wanted to advertise on your board?
You can only make so much money being a personal trainer, or pimping LBAs, or selling products like wrist straps and protein powder. You say yes once and greed makes it easier to say yes again and again.