Survivorship bias
Judging from the winners you can see, while the failures have quietly disappeared from view.
You only hear from the ones it worked for. The others are not lying about their results; they have simply stopped talking, closed the account, or never had a reason to post.
This distorts almost every money story you encounter. The trader with a track record is visible; the thousand who tried the same approach and quit are not. The fund with ten strong years is advertised; the funds that closed are removed from the comparison tables entirely.
It also distorts advice. Someone who took an enormous risk and happened to succeed will describe their courage. Someone who took the identical risk and failed is not writing a book about it. So the surviving advice systematically overstates how well the strategy works.
The useful habit is to ask what the failures would have looked like, and whether you would be able to see them from here. If the answer is no, you are looking at a filtered sample and should discount it heavily.
It applies to friends and family too. People report their wins.
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Covered properly in Learn.
This term appears in the glossary of The Quiet Fortune, Volume I.