Prenups are very attractive to wealthy people who marry someone poor, friendless, and/or ignorant.

They typically design them so that it's harder for the poorer spouse to leave, than for the wealthier, they exclude the poorer spouse from inheritance or sharing in the wealth generated during the marriage, and generally quantify the poorer spouse's homemaking and childrearing efforts as having no monetary value.

To add insult to injury, the poorer spouse can't afford to contest it in court, later, once they realize that they got screwed in more than one way.