It's more than just one thing. A lot of rich people value their career highly and wouldn't want to sacrifice the time for kids. That said, the correlation with

It's more than just one thing. A lot of rich people value their career highly and wouldn't want to sacrifice the time for kids. That said, the correlation within developed countries between income and how many kids you have varies IIRC, some places richer people have more kids, in other places they have fewer.