Billionaires are not a good model for what people will do if they don't have to worry about mortgages and bills, they're a model of what people will do when the

Billionaires are not a good model for what people will do if they don't have to worry about mortgages and bills, they're a model of what people will do when they have virtually no resource constraints whatsoever. If people don't have to cook, clean, give up vacations, sacrifice their hobbies and career goals, and can pay an army of servants to do any unpleasant childcare tasks, then yeah, I suppose they'll have more kids. From what I've read a certain number of people do say that financial constraints cause them to have fewer children than they'd like, but stated preferences are not far enough above revealed preferences for that to change the result. In Hungary Orban is virtually throwing money at people to have more kids but the population is still declining. Countries with robust social safety nets are doing no better than those without. The only exception I'm aware of is Israel, primarily due to the Orthodox community.