> "Support families to raise kids" sells way better than "let old people die if they don't have kids to support them."

Part of the problem is that the decision to not have children isn't a decision for many people. Some never find a partner (and no, I'm not talking about "incel" nutcases here - I'm talking about countries and regions with a severe oversupply of males), some suffer from medical infertility (e.g. due to injuries, cancer, PCOS, endometriosis), some from genetic infertility (e.g. people with genetic disorders, being somewhere on the wide DSD spectrum or where the partners are not genetically compatible), and some have no other choice than not having children for ethical instead of medical reasons (e.g. both partners are carriers of genetically passed diseases or suffer from mental health issues that make them unable to take care of a child).

You can't just go and punish these people for not having had children in their life, that's just as unethical.