Agreed, its a grey area. And the guys who think they're investing fall into this confusion and think everything will be OK if you just hold on long enough. Which would be fine if it were true and if they were able to stomach the losses and if time and bills etc. didn't catch up with them.
But some bear markets last for years, and when the bear comes, there isn't a way to predict when price will get back to the starting point. From the 2015 highs it took 14 months, from 2007 it took over 5 years, from 2000 it took over 6 years, from 1929 it took 25 years.
The best objective decision is to get into cash when prices are falling. When to get into cash is a subjective decision and whatever I suggest could have holes shot in it. But the mugs reject any such plan and that's their fatal flaw, not the exit timing or exit signal.
I don't want to be rude so I'm saying nothing about mean reversion trading.
Thank you tomorton! So when you say "The best objective decision is to get into cash when prices are falling." - what does that mean? How far, how fast? Those stats you gave give one much fear!