OT: How is extortion a crime?

"Pay me $1000 or I'll release these pictures of you and a goat" -> You're the jerk who did wacky things with the goat. If it were me, I'd gladly pay $1000 to keep it quiet. In fact, if I did something shameful (assume legal) and someone had pictures of it, I may approach that person and offer money for his silence. I want to keep his interests with mine.

Don't get me wrong "Pay me $1000 or I'll cut your wife's thumb off" -> Illegal, as it involves violence. But the former case is a simple transaction benefiting both parties.