I mean I try to be somewhat prepared for numerous long term world event possibilities. My principle aim is to have a portfolio which would likely do well even if I were to become comatose for 20 years. I always tend to avoid buying companies in industry groups with few entry barriers, such as food, clothes, consumer goods, etc. I am concerned that just about everybody is interested in stocks today. Just 20 years ago, this was not the case.
Financial markets seem to follow long term cyclic patterns, probably based on mass psychology.
After the last great rise and fall, ending in 1929, two generations elapsed before the masses again became enthused with stocks.