It may or may not be killing for fun.
PD's are varmints pure and simple. They destroy areas for crops and cattle. Not a good thing when you have a couple thousand dollar cow/horse fall in one the the holes and break a leg. When I was in HS, my Grandad paid me and my HS friends to come out and shoot PD's on our summers off. Pretty soon, we were doing several farms and ranches in the area.
Same goes for Wolves, coyotes, beaver, nutrias and wild hogs.
You would not believe how much acreage a den of beavers can damage.
BTW, to the antis, this is hunting!