It's immoral to leech off other people's children tax money, sure.

But also no one wants to be a sucker doing 20+ years of unpaid labor raising kids, so someone else 's S&P 500 keeps growing and sustains a very comfortable retirement plan, and no one will even help you with raising kids anymore.

It's really the system's fault, not individuals. It makes it lucrative for every individual human to give as little back, and take as much from everyone else.