If the market was actually rational the stock would have tanked already. The small number of people who hold the most stock have every incentive to keep the price high.
Tesla stock isn't based on whether they are a successful company, it's based on whether or not Musk is good at convincing people to put money into anything that's near him.
People who want to hold stock aren't the ones who set the price at which it trades. People who want to actively buy or sell it do.
You got Keynes's admonition against shorting right. But Tesla stock is impervious to reality not because of a small number of shareholders, but because an unusually large number of retail shareholders are in the cult of personality. It's a meme stock.
People who want to hold stock aren't the ones who set the price at which it trades. People who want to actively buy or sell it do.