can’t these assholes get any without threatening or buying it?
Probably. But it isn't all about sex. It's about power and control. For some deviants, it is as powerful as the sexual urge.
There are people who LIKE exercising power over others.
Consider the popularity of "Fifty Shades of Gray". Now consider that, in real life, there are men who like being in control, and NOT just in a play-acting scenario.
It goes FAR deeper and darker than just charity workers.