You don’t want just kids, you want well raised kids. Badly raised kids are easily a net negative, so just paying people to be parents isn’t going to work.

The only thing that might incentivize people to think about the long term is getting rid of all old age benefits (including continuous bail outs of broad market assets by the federal government by sacrificing the purchasing power of the currency).

Right now, we take productivity from people who sacrifice to raise kids well and give it to those who don’t raise kids well, or not have them at all.

This obviously leads to an arbitrage opportunity (as evidenced by DINK lifestyles).

I do not see any other way other than to remove this arbitrage opportunity. Which probably will not happen in any democracy due to old people’s voting power.

I beg to disagree. In Switzerland, a lot of emphasis is put on assimilation to a Swiss identity via pre-school and school. Now this eventually raises the bar for parents to raise their kids, but it also acts to Swissify immigrant kids quickly as well (and 25% of the residents in Switzerland are not born as swiss, many of those are refugees from African countries that America has problems dealing with). America's DIY hands off parent-focused system consistently has the worse results of all the world's developed countries, and is proving to be worse than even developing country systems.