Prosititution is the oldest profession known to man. I don't know if that is true, but I heard it once and it makes sense.
In Europe, it is a legal profession. You go there, the girls have certificutes hanging up on the wall to show they are disease free. It is a profession and they makes good money.
Men like sex, when they want it, where they want it, and with who they want it with. This is a perfect match for prositution.
Humans are naturally sexual. To deny this sexual urge is denying your instinct. (Yes, Even my ex-wife was strange enough to deny this urge.) Maybe that is why she is my ex-wife.