There is something between 'fundamentals' and 'irrationality' here. This kind of market cap results from a bet by buyers that, if given access to capital (by in

There is something between 'fundamentals' and 'irrationality' here. This kind of market cap results from a bet by buyers that, if given access to capital (by inflating the value of Tesla or Elon's holdings of Tesla shares, or its ability to issue more) Tesla will realize the value that the market cap is bid up to. But of course, it's circular - if Tesla's stock wasn't bid up that high, it wouldn't have the capital to realize that value. That doesn't mean it's irrational, but it's not the same as a cold evaluation that a business is already clearly going to be worth than much.