Statistically speaking, many of our ancestors probably had an above average number of children...
not relative to their time. in a world of weak institutional and little in the way of medicine, most children die before adulthood. those that do are your only insurance policy in old age.
> Having a billion dollars is like having a dozen children
You mean being a billionaire is like making up for ~5 childless couples not contributing to the next generation? Could be!