and then they didn't survive for the next generation. If that is okay with a society, nature will simply replace that society with another one.
Combination of the latest trends of the past few decades (contraception, individualism, nuclear families) goes against the natural design for the sustenance of our species. Nature doesn't have morals and is pretty ruthless, so if a sub-species doesn't want to have kids, it will cease to exist and will be replaced by the one who values kids.
South Korea will be an interesting example to watch - whether they reverse their course and start valuing kids as a society, or they might get replaced by immigrants or are taken over by the neighboring countries. Nothing good or bad inherently with either option because life is meaningless anyway.
When my partner in a childless relationship gets asked “but why?” when she says she doesn’t want children, her answer is this: “would you have asked the same question, had I said I want them?”