Polygamous men are the biggest philanthropists in society because they distribute or share their resources and wealth with multiple wives. Ensuring that women and their children are looking after.
The average man neglects his bank account and wastes his money on noncommittal, monogamous relationships with many women until he finds a wife. After that he is locked into a marriage where he is forced to hoard his wealth for only one woman, not distribute it to as many women as possible.
Let's face reality: Not every woman will get a job. Not every woman will be empowered. Not every woman will be educated. Not every woman will be rich. But every woman will have a problem trying to get a husband under monogamy. Because of the ratio of men to women. Therefore, monogamy is very wasteful and expensive!