I'll spot you "they" as the endless white nationalist nags and natalist pundits. For some reason "population collapse" never shows up as a concern for Palestinians or Cubans or Bangledeshis or Congolese. It's only ever a rich white European problem.
But this endless "I didn't start the fire" rhetoric kinda ignores how the prior generation as a whole had about as much control over their material conditions as we do now. Just being mad at The Olds neglects how many of them delivered the education and health care and technology and agriculture that brought us to the modern moment [in a good way].
Not to be all "you hate capitalism and yet cell phone" but you gotta see the prior generation as the same group of disaffected working class as we have in the modern day.
Ffs, our parents were inundated with "Overpopulation" as the crisis du jour. They were lectured over having too many kids and having kids when they were too young and not being economically independent enough to care for anyone but themselves. We inherited that from them and internalized it. And now we meticulously practice contraception because we've been drilled to believe it's the responsible thing to do.
Only post-COVID have we really seen the Natalist Panic taking off. It's a complete 180⁰ and largely the product of Millennial insecurities.