@soulforge I think the problem in such cases is that the man perceives himself as inferior (since he perceives her as superior). He accepts being treated poorly because that's what he think he must do to keep that woman, he fears being dumped if he stands up for himself.
I think that in itself is why it fails. He loses his spine, THE thing that women find attractive in a man, in the hopes of keeping her. What an inferior feeling man does to keep a woman is what drives her away. The woman doesn't have more power just because she's prettier or richer, it's men who surrender their power for such women.
I think such relationships can work out well, but it is VERY important that the man does not give away his power, does not accept unjustified poor treatment and walks away with his self-respect intact if she doesn't respect the man.
If a woman has more money or better looks than a man, but still wants him, then it was obviously something else that attracted her. So I think being hung up on money and looks is in that case very misguided. What is left must be who he is as a person, which quickly deteriorates if he is intimidated by her in any way. Meaning the very thing that attracted her is now gone.
So, never regard a woman as out of your league. Never put her on a pedestal above you (not implying you should put yourself on a pedestal above her, that will fail too). The moment you do you will lose everything she values in you.