I think people are putting too much emphasis on the financial costs, you figure it out as you go.
I have a 1.5 year old and it's hard to explain the simple joys I get from just running around the house with him goofing off. It's nice to forget about the real world for a while and build a pillow fort. He's also brought much joy to other family members (grandparents, cousins), and my extended family is closer as a result.
People who think about social policy on the scale of nations need to worry about costs.
This isn't something that you "figure out as you go", it's something that causes wars and societal breakdown. We're already in a democratic world where the key voting fault lines are young-vs-old.
I have a 1.5 year old and it's hard to explain the simple joys I get from just running around the house with him goofing off. It's nice to forget about the real world for a while and build a pillow fort. He's also brought much joy to other family members (grandparents, cousins), and my extended family is closer as a result.