Brian Chesky personally photographed every Airbnb listing in New York in 2009. He flew out with a camera, knocked on doors, watched hosts greet strangers, took notes on what felt awkward. Airbnb is now worth $78 billion. His framework was the 11-star experience. A 5-star stay: someone meets you at the door. 6 stars: champagne on arrival. 7 stars: the host pre-stocked your favorite groceries. Keep going. 11 stars: Elon picks you up at the airport in a SpaceX rocket. The exercise sounds…