Well, this kind of things are rarely purely about the sex. It’s not an hedonist desire for pleasure, but about the taboo exertion of absolute power and ownership over a person that is unwilling, or is illegal for them, to submit. Just like how some rapists aren’t doing it for the orgasm, but for the violence of subduing and dominating a person. Now, a healthy person would be satisfied with a fantasy, some would venture for a consensual role play. Psychopaths with unlimited power and money know they can access and usually get away with the real event.