When you're on a reality show, people can see you being a douchebag. They will remember how much of a douchebag you were. In the case of Big Brother, which uses live feeds, people, such as your employer, can take action against your douchebagginess while you're still in the house.
THIS IS NOT HARD. STOP BEING A DOUCHEBAG.
UPDATE: Why did I have to edit this to include an additional contestant? Why? Why did you make me do that?!