> OP is discussing a 30+ year time horizon, though. I can think of a few potential things that would precipitate not just a crash, but a long-term economic malaise

...

> Climate change

The climate change consequences big enough to cause a long-term economic malaise are far enough out to not affect most of today's workers. We'll mostly just get things that cause short term disruption, like more large storms, more weather variability, more record high tides, and similar things.

The big things, like sufficient sea level rise to require abandoning significant parts of many major cities, long term changes in water availability that significantly change agriculture for whole regions, and so on are usually forecast to be in the 100+ year timeframe.

This is one of the frustrating things about climate change. Over the long term it likely has disastrous consequences for humanity, but it can be largely averted or at least limited if action is taken early enough. But "early enough" puts you a time when the consequences are still localized and intermittent, and so it is easy for people to overlook it (especially when they can make more money by doing so).