I heard it was because the woman argued she was pressured into signing it or that there was a different VERBAL agreement LATER during the marriage that "nullified" the prenup.
It's basically whoever can afford the best lawyer.
The best lawyer can't even be figured out because the more you charge, the more people think you're good at being a lawyer and there's no standard of measurement.
Either way, you get married, you're gonna lose money if you ever get divorced. You cannot guarantee marriage forever. You don't need a "fault" for a marriage to be divorced (no-fault). It makes more sense to raise a family and have children out of marriage and raise them together with your "technically-wife" without signing any license.
I used to defend marriage... I used to be the biggest defender of it... I still believe marriage might one day be possible, but not under US law. I've been advised that if I marry anyone that isn't as rich as me then I should put everything in blind trusts and do sneaky financial things to hide my money.
I just don't see any way for marriage to continue in the US.