You buy when the market is low.
I remember about 15 years ago, catching a report on CNN (or somewhere similar), where they were talking about the 1987 Black Monday crash, and where some stock prices were at the end of that day, and comparing it to where they were at that time (around 1999). It was incredible how low some stocks were, compared to where they were 15 years later.
The smart investor in the stock market will look at any crash, and buy things up. I don't know that any crash will happen. If it does, I think it stands to be mineralized, because people are so much smarter about things like that now.
But, don't trust me. I'm no stock expert, but I did sleep at a Holiday Inn Express last night.