My take is that modern culture just doesn't want kids. It doesn't matter how cheap you make having a family, for many it's just not remotely the same culture as it was 50-70 years ago.

Then, for most, it was, at 20-ish, find a partner ASAP and have a family. That was "the culture".

Today it's "have a great career, travel, party, netflix, game, ... and maybe someday think about kids"

There's other stats like in the USA in the 50s, being single was seen as just a transition until you met someone. 78% of adults were married, 22% single. Today, being single is way more common, > 50% and while many of those might want a parter, tons don't see it as a priority.

It’s literally the only purpose of life to pass on our genetics to our offsprings in a Darwinian sense.