>that has never happened

This is the part that I disagree with. Talk with anyone who planned on retiring around 2008-ish. As a hypothetical, if the market is the proxy measure they lost around 5-8 years of retirement because they had to have "more time in the market" to re-coup losses. If they actually retired and were drawing down their money, it's even worse. Granted, the hypothetical is biased because someone of retirement age shouldn't have that much market exposure, but the point still stands that, while true at the population level, waiting for the market to recover doesn't always work out well at the individual level. I tend to think the people who tout long-term averages of market returns tend to ignore the long periods of sideways or downward movement that may align with an individual's specific circumstances.