Investors who buy and hold like 401K participants who buy every two weeks and average in have done brilliantly.
We'll see if that continues. This market is so overbought it's crazy. I'm preparing my shopping list for when it comes back to earth.
If you were using longer term "overbought" technical indicators like RSI or MACD as a basis for shorting the market for the past decade you got crushed. Obliterated. Many times over.
I use common sense and history. Growth occurs in cycles and we're coming to the end of this one. If you think the market and economy can just keep going up indefinately, don't let me stop you, it's your money.
You should have an open mind. Have you run a "running window" analysis of 401K/IRA returns using @bone's method? I ran that test for me/my generation using SPY and we came out great. I bet if you use a 30 year time horizon, most should come out fine, even after the 1987 crash, the 2000-03 crash and the 2008-09 crash. Even if we retired right at the end of the crashes we should be fine because we don't take all our money out at the bottom and keep it in cash under our mattress. The market usually recovered.