[rich_sasha]

> Would a shrinkage still cause economic collapse?

Sort of maybe yes.

Even when you save up the cash up front, you live off return on the investments. Of course you can invest globally, but wherever you invest, you rely on there being a young productive workforce to generate said return on investment.

Ultimately, cash is a nice abstraction, but you need someone doing the actual doing - harvest food, run hospitals, fire stations etc. With many old people around, there's many people who need services (especially health) but few to run them.

Where you are better off is you ringfence the saved up cash for investments, ensuring you have more growth to finance the whole party when it comes to it. In principle the state can do it too, but it's often too tempting not to.

[bryanlarsen]

Exactly. No matter how much you have saved up, inflation can destroy it. If you need nursing care and there aren't enough nurses, they can set their own price. The overall inflation might not be bad because stuff like housing gets cheaper with a shrinking population, but if what you need is in short demand, you will pay more.