Good artists gone bad

Lately I have been thinking a lot about those gifted individuals who choose to use their powers for evil. What the devil is going on here? How can a writer as talented and funny as Stephen King continuously churn out such horrendous garbage? How can an mc with skills so good that he can pay his own bills, namely 50 cent, do likewise (substitute bling and hos for psychos and the undead)? I am sure there is a long list of these people, people who would use a shotgun to kill a small rodent. To quote a police officer I was chatting with, "Pow! He was gone! I sprayed that little shit all over the yard! I couldn't even get near him with the Glock."