wealth doesn't imply a greater number of offspring
It did in preindustrial times, which is to say for practically all of human history. I recently read a quite impressive study of birth records in a scandinavian country (forget which) that showed a significant difference in the number of surviving children of rich and poor women.
I would argue that in preindustrial times the rich and the poor were on different sides of a subsistence level income. This was a huge distinction until recently, but in the present day Warren Buffet doesn't have a harem, nor does he have several hundred children. Wealth and progeny don't scale.
It did in preindustrial times, which is to say for practically all of human history. I recently read a quite impressive study of birth records in a scandinavian country (forget which) that showed a significant difference in the number of surviving children of rich and poor women.