Having kids early precludes education and career focus -> Education and career focus gets you money and prestige -> Folks want money -> Folks want to avoid having kids early -> Fewer kids.
It's all based on a couple misconceptions that a) you can't have what you want now if you have kids and b) you'll want what you want now when you have kids.
Try this thought experiment on for size:
Initially, you don't have kids b/c you don't want to avoid this vacation ($5k?) and that opportunity (A few years at a good job?)
But consider the reverse: If you had kids, and they were going to die if you didn't turn over $X, what value of X is "too high"? There is no value of X that is too high, you'd happily give everything you have to bring your kids home safe. Why don't we give a meager few years of our lives to have kids and get them through the infant stage until our lives return somewhat to normal?
Why do we all pretend that $5k before kids is somehow not the same as $5k after kids? It's not a trap - parents do want their children, do love them, and are willing to drop money to have them, but we only recognize this after they have them. Substitute money for a job change, a spouse choice, etc.
It's a weird cognitive dissonance that we don't recognize this for ourselves when we're young, and I'd argue it's mostly this cognitive dissonance that stands in our way. So, some tangible improvements and a slight increase in number of successful people having kids would probably dispel that misconception.
Well I'm super happy that I never had kids. I'm nearly in my 50s and I still live as a younger person because I never had to have much responsibility. As such I can enjoy my own life much more. I still go out dancing until 6am every weekend and move to a different country every decade or so. I couldn't do any of those things if i had a 'stable' family.
