I can't think of anything you can compare today to. Don't know how the market reacted during the Spanish Flu, but pretty sure the internet and their government conspiracies weren't around then.
The market was bloated for sure and I've been saying, if everyone is a millionaire then no one really is.
What I see in our future is too much cash existing and thus, having a million dollars is like having $550k 6 months ago, very shortly.
People need to get out of the idea that being a millionaire means you can retire.
With that said, staying out of the market all together is like burying your cash in the backyard back in 1950 and now digging up that $100 bill.
Buy on the way up!!! Just my opinion, of course.