A, B, and C have existed in most societies below a certain threshold of per capita wealth, regardless of whether or not polygamy was practiced, so you may as we

A, B, and C have existed in most societies below a certain threshold of per capita wealth, regardless of whether or not polygamy was practiced, so you may as well throw those out. And essentially every single highly developed country with an economy that is not primarily dependent on resource extraction has a long cultural history of enforced monogamy. Correlation != causation and all that, but I sure as hell wouldn't bet on polygamy being a societal arrangement conducive to human flourishing.