If you're investing long term, wouldn't the best position would be cash until a once in a generation stock collapse happens?

I don't know if it's a silly idea, but like the title says. If I'm investing and not selling my stocks for 30 years. I bet in those 30 years at some point there's going to be a black swan event that hits stocks hard. Why not buy then? Previous examples would be dot com, housing bubble, covid etc.

I know there's the whole catching a falling knife and timing the market things. But it's pretty obvious when the whole world is going to crap that you can DCA on the way down and as it reverses.