The "No Harm, No Foul" rule is simply wrong – as per the lovely anecdote told by wise investor-philosopher-professor Benjamin Graham ("Current Problems in Security Analysis", Lecture, New York Institute of Finance, 1947) quoted in the Hussman Funds Annual Report for 2023:

I recall to those of you who are bridge players the emphasis that bridge experts place on playing a hand right rather than on playing it successfully. Because, as you know, if you play it right you are going to make money and if you play it wrong you lose money – in the long run. There is a beautiful little story about the man who was the weaker bridge player of the husband-and-wife team. It seems he bid a grand slam, and at the end he said very triumphantly to his wife "I saw you making faces at me all the time, but you notice I not only bid this grand slam but I made it. What can you say about that?"

And his wife replied very dourly, "If you had played it right you would have lost it."

_{(cf Lecture #10 of The Rediscovered Lectures of Benjamin Graham, and Capital Ideas (2000-04-08), Bubble Busters (2002-02-06), Harry Browne Rules of Financial Safety (2019-12-24), Shiller Price Earnings Ratio (2021-03-29), Irrational Exuberance (2021-08-13), ...) - ^z - 2023-10-02}