Earlier quoted context omitted.
The trick is, you don't invest during the downturn, hence all the cash hoarding. You invest after it bottoms out for a while. Macro economies do not recover like a rocket, the window to invest is very large, so large that if you only recognized the bottoming out a couple years later, you still haven't missed the opportunity.
That is a really interesting point. So I've never invested in stocks before (preferring to invest in my own business) but have decided to diversify and am only seeking returns in a 5-15 year bracket (but want to minimize 1-5 year downside so it could potentially work as an extra emergency fund too). I had assumed being 20%+ off of the highs, it'd be a good idea to start getting involved now, but.. maybe I should wait…
That said, my opinion is this: there's far more risk than potential reward in the market right now, even after this drop. This is probably the beginning of a bear market that could last, I don't know, anywhere from maybe 6 to 18 months. I would definitely not suggest buying until it's clearly over.
EDITED to add: here's a good summary: http://seekingalpha.com/article/3825236-bear-market-phases-s...