Success in one domain breeds confidence that feels transferable. A brilliant surgeon feels qualified to opine on economics. A successful entrepreneur feels qualified to redesign education. This confidence is sincere but dangerously miscalibrated — expertise does not travel between domains as smoothly as it feels.

The illusion has a kernel of truth: some meta-skills do transfer. Discipline, analytical rigor, and pattern recognition help everywhere. But domain-specific knowledge — the details, edge cases, and hard-won intuitions that make an expert — does not transfer at all.

The test is simple: in this domain, have you made enough mistakes to learn from them?