>what is it about being rich that causes you to have less kids?
Are we talking locally rich or globally rich?
People in industrialized (rich) nations don't have tons of kids because that's not how you get ahead in that kind of economy. Subsistence farmers have tons of kids because that's how they get ahead economically.
Within richer nations richer people have fewer kids because the way social safety nets and social expectations of how one should raise one's kids make kids more expensive the higher up you go.
Are we talking locally rich or globally rich?
People in industrialized (rich) nations don't have tons of kids because that's not how you get ahead in that kind of economy. Subsistence farmers have tons of kids because that's how they get ahead economically.
Within richer nations richer people have fewer kids because the way social safety nets and social expectations of how one should raise one's kids make kids more expensive the higher up you go.