Indeed. Let's start by getting rid of the welfare state and bringing back the greatest incentive to child-bearing... care in old age.
I'm serious. One thing I often see is complaints that the younger generation (typically millenials) are not pulling up their end of the bargain. However, neither are their parents. Typically, one would expect to become a grandparent that cares for their grandchildren. In return, your children take care of you. This is how humans have lived for generations. Yet, today, seniorhood is treated as a second adolescence. Grandparents neglect their grandchildren while parents are forced to do it all, so to speak. It's no wonder they have no time for kids.
Human childbearing is exceptionally hard. It's why human males take part in the child-raising typically (women with committed men have more children on average and shorter spacing between pregnancies). Moreover, it's why natural selection has typically brought about kin groups that care for children. Social security is an affront to this entire arrangement. There's a balance to be struct between guaranteeing no one is destitute and not shifting expectations of the elderly to the point where living purely for themselves is actually considered acceptable.