The Great Wall isn’t visible to the naked eye from orbit. A fact repeated a million times can still be wrong.

Repetition does something to a claim that only evidence should do. Hearing a thing often makes it feel familiar, and familiarity gets mistaken for having checked it, which is how a tidy piece of trivia survives for decades after the people who could actually see from orbit said otherwise. Popularity measures how easily something travels, not whether it is true.

Pick one fact you have repeated for years and look up where it came from. Choose one you would bet money on, since those are the ones nobody ever tests. Finding a single familiar thing to be false does more for your judgement than learning ten new ones.