I think you are right about it being miserable people. People who have forgotten how to have fun and just enjoy life. I think its linked to the hustle culture, and the need to constantly do something (even if its just doomscrolling).

There is also a tendency to treat children as a strange species rather than as human beings. I think that is older but its become worse as people come up with more and more parenting approaches, write books and make videos about it, etc.

Its sadly not just an American problem. At the very least an Anglophone problem.