You cannot understand the declining fertility rates worldwide unless you understand and internalize this graph:
https://ourworldindata.org/parents-time-with-kidsBeing a parent today is substantially more demanding than it was in the past and this has very wide-raning consequences:
1. While the monetary demands have increased, they are not a huge factor. That's why in places with generous subsidies and cash transfers, the impact on fertility has been positive, but pretty limited.
2. There's a backlash against "wokeness" and women's rights. being a father was easy and spending your nights at the bar with your buddies was perfectly socially acceptable. The demands on being a "good" father today have risen substantially, more so than for women, and some men cannot bear this new burden. But rather than admit weakness they try to point the blame on women who demand the burden be spread equally.
3. People have pets instead of kids. The money, care and attention your average tech worker's dog or cat receives today is probably the same as the average person devoted to their kids in the 50s. That is to say, people's preference for taking care of living being and companionship has not changed much, but many people have been "priced out" because of the new demands. In other words, many of the people you see with pets but no kids today (or pets and one kid) would have been perfectly capable and happy with kids in the past.
If you believe this, as I do, than it's bad news because there's nothing easy on the horizon that can fix this. Cash transfers and subsidies help a little. Support from companies for parental leave help a little. Humanoid house robots could help a lot (imagine a $30k TeslaBot that can do all your housework, no more cleaning, garbage, cooking, tidying, laundry or yardwork), but then the demands for childcare could just take this into account and keep increasing.