It's hard to know large numbers of other people's motivations. My first guess is that some men really resent that they can't get sex for their intrinsic wonderfulness, and prostitutes remind them of that fact.

On the other hand, I don't know whether men who hate prostitutes don't have non-monetary sex.

Looking at it from the outside, it's just weird-- it's like resenting restaurant cooks because they aren't making home-cooked meals for their families.

So far as money is concerned, I've seen a man describing women as "sitting on the bank", but that seems to be resentment of women for having a source of financial security that men don't have.