They went back where they came from, the world of fairy tale math.
The same world where “retirement” has always existed throughout human history.
Pensions suffered from poor timing, coming into existence as life expectancy rose. Paying in for 30 years and then living five more in retirement was a reasonable and financially feasible model. Working 30 years (25-55) and living 30 more (55-85) was not feasible.
Pensions went bankrupt when unions demanded more in benefits in retirement than workers every contributed, early retirement in luxury and free medical care.