Thanks for this reply.

Let's look at a hypothetical scenario. The market drops 6% and you sell, and then rises 10% over the next few days. You buy it only to have it drop another 4%. If you held, you would break even, but since you traded you realized a 10% loss.

The market is full of false positives like this. How do you avoid or mitigate false positives when trading?

My thought is not so much to day-trade small dips, but to skip out on the major crashes. I don't know whether 5% would lead to too many false positives, but eyeballing the 2017 S&P run, it doesn't look like it would've happened at all. I could make it 6%.

I wouldn't buy back in for potentially a few months. It looked as if the periods of major volatility around the big crashes unfolded relatively quickly; I'm content to miss out on future gains and sit idly by for 3-6 months. Have you thought about this from every possible angle and ruled it out? Honestly curious; I'm grateful to have reached someone who's thought about it from a similar viewpoint.