When thinking about the last 20 years, investors easily recall the tech bubble, the financial crisis and the flash crash in 2010 that together form the most recent lost decade for equities. These negative events dominate our decision making. The (more important) 300% return from equities during this time does not.
For all the time spent worrying about bear market risks, the overwhelming majority of short term traders and professional fund managers haven't found a way to avoid it. And if they have, it has been at the expense of also missing out on the gains during bull markets.
If you are going to do better than most, it won't be by continually anticipating a market crash. That has invariably been an exit ramp onto a dead end street. Tuning out noise and consistently following investment rules and hard data is far more challenging than it sounds, but the performance of those that who do it can be in the top 5%, maybe the top 1%.
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If you are in your 40's or 50's, you will probably endure another lost decade like the 2000's, where stocks did not appreciate on a net basis. If you are in your 20's or 30's, there's a good chance you will endure at least two such periods in your lifetime.
The future could turn out different than the past, but the pattern over the past 120 years is that expansions alternate with long periods where equity markets churn sideways. That's true even if you include dividends and assume dollar-cost averaging (DCA). The chart below shows the length of time US equities have spent getting back to breakeven from a peak (from Lance Roberts; read his recommended article here). Enlarge any chart by clicking on it.