This is a very interesting perspective to me, because I know it’s relatively common in non-Western (or maybe just non-American?) cultures that parents move back

This is a very interesting perspective to me, because I know it’s relatively common in non-Western (or maybe just non-American?) cultures that parents move back in with their kids when they get old, or more generally that extended familial units are far more cohesive than they are in the States. ....Which then means your extended family (and own children) are indeed a ‘retirement plan’, because the expectation is that they’ll be around to support you when you’re unable to support yourself. But the intensely individualistic American lifestyle doesn’t lend itself to that thinking very well, so there’s less incentive for folks to have kids for their own interest. (Indeed, as a mid-20s couple, we’re more often told the ways in which children _limit_ the lives of the parents, rather than augment them.)