Having fewer children is something that is positively-correlated with a society being wealthy, rather than the other way around.
Correlation is not causation, there’s no “other way around”…
But what you’re talking about is the drop in fertility due to industrialization and other periods where children worked less and cost more.
That’s different than what I’m talking about; when a labor supply shrinks it means workers get paid more.
That’s just basic supply and demand.
We’re both right, just talking about different things.
Or we could just tax the wealthy…