There are tangible problems with a low birth rate though, which western economies are experiencing now.
People don't owe their parents anything, but they naturally do at least give a shit about them - provided they had a good relationship.
Less kids, less adults who would volunteer to do it.
But of course not everyone lives like this and many have a horrible quality of life at the end so there is room to improve. One improvement is cultural I think: we shouldn’t be hanging on to every last strand of life possible, and should make it easy for those with little prognosis for quality of life to die gracefully in a way of their choosing.
In any case certainly more adaptation is needed, but I see signs of the development.
People aren’t paying attention because from a raw numbers perspective our population is growing. But it’s also aging, and eventually people will die and we won’t have created enough kids to reverse the shrinking.
I’m not even getting into the economic catastrophe of a shrinking population caring for an aging society. The US may be alright due to immigration but you can’t say the same of Korea, Japan, Italy, or most of Europe.
This is a crisis and we need to be taking action right now. By the time the populations start shrinking it will be too late. We can eventually reverse the trend but it will take an entire century, or more. We’re quite literally running out of time to avoid disaster.