What does the psychology behind this have to do with anything?
It has a ton to do with it. If it didn't then why is there such a taboo (for so many women in the industry - as well as in society) about crossing over from nude modeling to making hardcore sex videos? The money is generally better in the latter, so if, as you contend, all of these women are equal in their mercenary sluttiness, why do most of them chose not to do hardcore?