That's deeply unfortunate if you were planning to retire next year, but you might just have to live simply for a few years while the market recovers.

Otherwise, no big deal unless we reach Russian or Argentinian levels of collapse.

That's possible. The East Asian demographic cliff, a US debt crisis, global soil collapse, there are plenty of imaginable scenarios.

But none of them have happened yet, unless you live in Argentina or were a Soviet citizen. The west could continue to get lucky.

Unless everyone has YOLO'd their entire retirement into NVIDA the AI bubble burst isn't going to wipe out retirement savings to zero. Even the worst drop in the US stock market in history (which triggered the great depression) eventually dropping 90% at its worst recovered nearly half loss in 2 years. Even that drop wasn't in one day, it happened over months.