If you're not worried about your investment for at least 10 years, that's one thing, but if you're already retired and watching your portfolio drop by 40% in a bear market, you're in deep doo-doo.
I cashed out of the market a couple of years ago, and while my returns during this period were meager, I at least had no losses whatsoever since then.
I'm selectively buying back in now in stocks that were especially hammered, and to say that has worked well would be a huge understatement. It is not folly to time the market as long as you have a rational basis for doing so.
Of course, guessing correctly helps, too! ;-)
You did have losses.
There's an old saying in economics, 'Opportunity cost is opportunity lost'.
I'd suggest you buy back into the market at a steady rate over a set period of time (called dollar cost averaging), getting into low-cost, stable funds, well diversified. Check out Vanguard funds.
You'll be glad you did.