Earlier quoted context omitted.
At a global scale, ownership of assets isn't really savings. Imagine an island society, with a bunch of 40 year old workers. You own the company that gets all the profit from their labour. So, you have a real resource, which you could trade with other places. Now of course this island has no children. How do you feel about your investment once the workers reach age 80. It wouldn't produce very much. In fact you'd nee…
Savings are invested into creation of long-lasting capital goods that are just as real as grain reserves or oil stockpiles, and that yield a positive return over the original investment - companies being "massively more productive per worker" isn't the exception, it's (hopefully) the rule. Yes there is risk involved and some investments won't work out, but that's why you diversify and make conservative assumptions. (…
Such a society would nonetheless face much difficult if the worker/retiree ratio changed from 100:0 to 20:80. That's true regardless of individual productivity level: case two is harder than case 1. Regardless of capital stock such as ports, rail lines, buildings, etc