Otis proved his elevator safe by cutting the rope live

Steam-powered hoists already existed for moving freight, but no one would ride one as a passenger elevator: every rope or chain eventually frays, and a snapped rope meant a fatal fall with no way to stop it. Publishing the technical spec of a new safety brake wouldn't fix that — buyers and the public had no way to verify a safety claim they couldn't see happen for themselves.

Otis had built a spring-loaded safety catch that clamped onto the guide rails the instant a hoisting rope lost tension, but a device is not the same as a belief. He needed an audience to witness the exact disaster they feared, watch it happen, and watch it fail to kill anyone — not read a specification sheet.

At the 1854 New York Crystal Palace Exhibition, Otis rode his own elevator platform up in front of a crowd, then ordered an axeman to cut the only rope holding it aloft. The platform dropped inches and caught — the safety brake had engaged — and Otis, still standing on the platform, called down that everyone was safe.

Staged the exact feared disaster live: rode the platform up, had the rope cut, and let the safety brake catch him, turning a claim into a witnessed fact.

The crowd witnessed the worst-case scenario fail to kill, converting fear into observed safety.

No trust in Otis's word was needed; the proof was direct and personal.

The demonstration addressed the exact fear driving refusal, not a lesser version.

Risk perception responds to vivid witnessed evidence more than technical assurance.

When fear is vivid and specific, stage the exact disaster and show it fails, rather than publishing specs.

Wikipedia states that demand for the safety elevator 'began to rise' after the demonstration; Otis installed the first passenger safety elevator in commercial service at the E. V. Haughwout Building in New York in 1857, three years later. Neither source read for this case gives a precise sales figure for the intervening years.