tending to be more negative for parents facing more challenging conditions

I think the above point of the study is key. If you are already facing significant challenges in life (economic, psychological, physical, etc), adding kids is not going to make it any easier, and might make things worse. I know it's anecdotal but I'm personally pretty satisfied with my life, and that's continued to grow alongside my kids. But as I mentioned in my previous comment, I have the resources and support I need to make that happen. I also live in a country that provides a lot more support to families than somewhere like the US. Not going to say having kids is all muffins, puppies, and unicorn farts all the time. But it's been fulfilling to me, and if I had to go back and do it all again with my kids, I absolutely would.

So in short. Having kids in a country that is not driven by money hungry oligarch means both higher satisfaction in life and higher meaning in life. Welp sounds about right.

Nice. Thank you. Even better, it's a free study.
But instead of showing the coefficient of the model they derived, I would have shown figures 1 & 2 which are riveting to me.