Indeed, such ignorance on HN these days.
What does that even mean? I also don’t think “nothing left to lose” was really the attitude of the post-War world and (especially) the US.
Alternatively you lived in a city reduced to ruins by the war, everything you knew or had is gone and you have no idea when or even if you'll be able to recover. Having a child doesn't involve as much of a concern over whether or not you can give them a better upbringing because things couldn't really get much worse in the first place.
Now, on the other hand, if you're talking about post-war, the world was recovering, there were opportunities everywhere, the future was looking more hopeful. You could just have kids and trust that they'd live a more comfortable life than yourself.
Nowadays, we're at this awkward point where there's just enough uncertainty and instability in the future, yet not bad enough that people have nothing to lose that people would rather wait or just not have any kids at all.
And in the 50s the future was looking good in some ways, but people also lived under a visceral fear of nuclear annihilation. These are all just feelings people may or may not have.
Ultimately, I think it’s much more complicated than saying that circumstances in the past made it easier for people to decide to have children.
With how poised American infrastructure is for a huge wave of massive investment and upgrades, the economic boom following that will more than justify the increase now to fix what's left of the covid supply chain crunch.