I'd also add to this point: https://wtfhappenedin1971.com/

The implied causation : https://en.wikipedia.org/wiki/Bretton_Woods_system

Bretton Woods was a defacto global* monetary system with other currencies tied to the dollar, and the dollar convertible to gold at a fixed rate. Nixon ended it in 1971, at which point the government was unconstrained by any external forces when determining economic policy. The debt to GDP ratio in 1971 was about 35% and declining. Today it's 122%. Even before COVID it was 105% and rising.

If this is not sustainable, then there will be a generation which will simultaneously be the last to benefit and first to suffer for this.

If that period really was remarkable, I think the outcome of a worse period is just lower expected returns, not the end of the world. Japan is often used as an example. But, if you invested regularly in Japanese stocks over that period of stagnation, I think with dividends its still a fine investment.

The FTSE 100 is almost at the same level as in 2014, those betting that the S&P 500 will always be different than the rest of the exchanges/indeces might be in for a nasty surprise.

Read Nassim Taleb books. No guarantee that history will repeat itself