As Tesla surged past Ford and General Motors last week to become the most valuable car company in the United States, here was the brusque assessment of Bruce Greenwald, a professor at Columbia Business School: “It’s nuts.” And, in a way, it is nuts. Particularly, if you ignore the Elon Musk mythology and look at the numbers. Tesla sold 80,000 cars last year. GM sold 10 million, meaning it exceeded Tesla’s annual vehicle sales every