In Lincolns day, conventional wisdom was that the US population would surpass that of Chia by now. Back then, the typical US family had many children, who helped on the family farm. Extrapolate a typical six child family structure, you expect a trebling of the population every generation.That did not continue, even tho surges of immigration came from Europe. Families today are much more likely to be two or three children than six or eight. Today adults think in terms of how they will afford college for two or three, rather than considering children to be farm hands and, ultimately, security in old age.
If you reach a comfortable retirement, you consider passing on to the kids enough to pay off the cost of Social Security which they are paying for but which is pay-as-you-go as far as the government funding is concerned. And hope that they will be able to do the same for your grandchildren.
I will never reach a “comfortable retirement”.
Our upside down pyramid is going to collapse into dust.