Let individuals decide how much they want to spend for their women (or men?) and children.
If a billionaire want to spend $100 million for 10 kids, it’s his right. If he wants to spend “only” $1 million or $100k for each kid, and produce 1000 kids instead, it’s also his right as long as the future mom also agree. Let the parents decide.
If government has a say it should be some minimal amount applicable equally to everyone or adjusted by kids’ need. Parents’ financial capability is irrelevant.
Rich men have more houses, more cars, more yachts, but less kids. Why?
Simple. It costs far more for a rich man to produce and maintain kids than for the poor. The same car cost the same to the rich and the poor. The same house cost the same for the rich and the poor. Yet breeding and raising a kid is far costlier for the rich than the poor.
Some of the costs are natural. Rich men do want to spend more money for their children. However, a child need is limited. Once you spend $1 million per child, there’s probably nothing else you can do to make that kid any happier or more prepared to get rich and successful in real world.