AI health tools are growing fastest in the exact conditions where their errors matter most. The Gallup survey found that 59% of people who use AI for health information are researching before doctor visits — a supplemental use that looks safe. But the same data shows 14 million adults skipping care entirely after an AI interaction, which is not supplemental use. It is substitution, happening in a population that already distrusts or cannot afford the system the AI was nominally meant to augment. When substitution is driven by cost and…