the.com/survivorship bias

means The error of drawing conclusions only from the people or things that survived some process, while the failures go uncounted and invisible.

from Coined within 20th-century statistics, the phrase got its signature story from WWII analysis of aircraft returning from combat: engineers initially wanted to armor the spots on surviving planes riddled with bullet holes, until statistician Abraham Wald pointed out that those planes survived despite those hits — the real danger zones were the unhit spots on the planes that never made it back. 'Survivorship' names the quiet statistical sin: counting only who lived to be counted.