This is a Lexicon entry: the mechanism, when it shows up, and the countermeasure. The full correction, with real-world cases and the audit prompt, hasn't been written yet.
When it shows up
Believing your work ethic is rarer than it is. Assuming your political views are more independent than average. Thinking your taste in music is more distinctive than the data would suggest. Entrepreneurs who believe their insight is uniquely original when dozens of competitors see the same opportunity.
Failure mode
Overvaluing your competitive advantage. Underestimating the competition because you believe your strengths are rare. Building strategy on uniqueness that does not exist. Related to but distinct from the better-than-average effect: this is about perceived rarity, not perceived superiority.
Countermeasure
Ask: "How many other people probably think the same thing?" Seek data on actual base rates for the trait or ability you believe is rare. Apply CL-2 (Base Rate Check).
Related traps
Also connected in the mapSelf-serving Bias·2 more, locked
Read next
Entry #96 of 631 in The Lexicon · see the full Lexicon