> Social security and pensions, for example, are structured not unlike a pyramid scheme: for every old person we should have more than one working young person.
Canada saw the demographic writing on the wall, and solved its public/government pension problem in the 1990s:
* https://en.wikipedia.org/wiki/Canada_Pension_Plan#1998_refor...
Good book on the history of the CPP, and how the reforms were determined and enacted (Fixing the Future by Bruce Little):
* https://utppublishing.com/doi/book/10.3138/9780802095831
There's no reason other countries could not have done something similar earlier (or even now).
In France it is reported that retirees now have higher (average?) incomes than workers:
* https://archive.is/https://www.thetimes.com/business-money/m...
This is completely ludicrous. For retirement planning purposes, it is often recommended to assume you'll need 70% of your working age income for the same lifestyle (you have fewer expenses—live not having a chunk of your income go to retirement savings), but in many situations it could even be ≤50%:
* https://archive.is/https://www.theglobeandmail.com/globe-inv...
To have the same (or more) in retirement generally means you "over saved" while working, and you could have had more resources for enjoyment of life earlier (after all, we don't know when our time will come).
> In France it is reported that retirees now have higher (average?) incomes than workers
It may not be exactly true, but it's close to be true, and then like you said the workers have way more expenses (rent, children).
I will point out that in the 90s we in France already knew that the retirement system was unsustainable. It is quite obvious if you look for 2 seconds at the population pyramid :-)
Generations of politicians tried and failed to do something about it, thanks to the left (and sometimes extreme right wing) saying that there was enough money and we just need to tax the rich more.