[seec]

You wouldn't get a collapse, but necessarily a contraction, the pie is getting smaller regardless, having less people to "eat it".

Yes, having a system based solely on positive demography isn't any good. In fact, I would argue that the reverse of this scenario is much worse. No matter what some would like to pretend, ressources are finite on earth and if you have a population big enough that deplete them faster that they can be renewed/recycled it is not good.

In any case I think it's wrong to look at it as a purely economic problem. It seems logical that one should be accountable for one's own retirement.

Previously this was done by having kids, because regardless of the economic situation they could always build on what the parents had and it doesn't take much to support your elder (unless they want a luxurious lifestyle).

Part of the problem is that the old generations (especially the boomers) have re-routed ressource distribution to themselves and you have an overspending on the past at the expense of future building.

The incentive around the providence state and pensions were all wrong in the first place now people are surprised that the results are undesirable (usually the one who advocated for the system).