Thank you for your kind words, Jamie. Thanks also for bringing up that scenario. You're of course correct in that such a scenario is the worst one for holding a substantial cash allocation.

However, since what I did was take out and move into cash my excess returns above those of the market's overall return in 2020, I'd be no worse off than had I invested in (say) Vanguard's S&P 500 fund in 2020 and stayed fully invested in it. In fact, I'm further ahead by that extra risk-free 19% that's sitting on the sidelines as insurance against a crash.