Investments doing so well these last 40 years is the unusual part. Vast majority of the gains in the stock market over its history happened from 1977-2007.
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.
Europeans have significantly different attitudes and values towards work and the economy, not to mention constraints. It certainly shows what's possible, but I don't think it's a great comparison.
