You're naive if you think that in the richest moment in the world history people are not making children in the richest regions for financial reasons.
That's nonsense. Poor people always had kids, still do. What changed is that people aren't able anymore to make sacrifices, huge in time and money for kids.
I would add to this is that the social pressures for having children have significantly diminished. I see a lot of people commenting on the side that having kids has become more difficult, which there may be some truth to but what people seem to ignore is that it has gotten a lot easier and more enjoyable to be a single person without kids. Society has adapted to this new cohort of childless adults and are catering to them in new ways.
That's nonsense. Poor people always had kids, still do. What changed is that people aren't able anymore to make sacrifices, huge in time and money for kids.