Consider where that initial cash came from. You worked your ass off between 18 and 60 and you got a bunch of cash in exchange. Some you spent on consumption, some you saved for use later. In fact, cash is just 'tokens for exchange later' where later is a time window that varies from 1 hour (hand-to-mouth) to 50+ years (surplus productive capacity people).
Wouldn't it be great if you could use your tokens for their promised exchange-value through your retirement and see those years of hard work payoff? In fact, multiply, because as you said the population grows, more goods are produced, and your cash tokens buy more and more of those goods.
It's a great way to retire. Unfortunately for the retired, they are on fixed incomes (pensions) in an inflationary world: those people get SCREWED to the extent where they can't afford heating in some US States.
These are people who worked hard all their lives and just wanted to live off the proceeds, the surplus they had generated.
Think of the chi^H^H^H grandparents!