Well, sometimes it's because your friends are on the board of directors, and they are doing you a favor (with someone else's money) in the hopes that you will return the favor to them when the time comes.

Or sometimes the CEO stacks the board with his buddies, so he almost certainly won't be fired and any votes on pay increases will sail through.

And don't forget including your culture's belief of how steep the power law curve of rewards is supposed to be.