The problem isn't that it's a ponzi scheme. It's that humans have to be replaced the same way anything with a finite lifespan (e.g. cars, buildings) has to be replaced.
In theory your children are your pension deposit. People who don't have children should get a significantly reduced pension or they must provably support the children of a family that has more than two children per woman.
The problem with modern society is that you need children at the end of your life. Agricultural subsistence requires children very early. It's a scheduling mismatch that causes people to delay having children all the way until they are no longer fertile.
In theory your children are your pension deposit. People who don't have children should get a significantly reduced pension or they must provably support the children of a family that has more than two children per woman.
The problem with modern society is that you need children at the end of your life. Agricultural subsistence requires children very early. It's a scheduling mismatch that causes people to delay having children all the way until they are no longer fertile.