[rayiner]

In east asia, and historically in the west, peoples' kids too care of them when they were too old to work. The idea of a bunch of retirees living independently at the same standard of living before they quit working, across the huge swatch of society, is completely without precedent.

[cpleppert]

That was when people were generally a lot poorer than they are now and having children had little cost beyond food. Now, that math simply doesn't work.