Note that while interest rates remain low almost every asset manager is going to remain invested. So are people like Buffet. Invest in Index. Don't pick stocks.
Interesting you should say that. That is exactly my theory as well. If you sell you have to put your capital elsewhere. Historically, interest rates gave a decent return in cash and bonds. That doesn't exist today. That's why you're better off sitting out any falls - as the one in March has shown, they are very short term.