The best way to justify that high p/e would be for them to use it to buy out the competition.

It costs Tesla ~<6% of market cap (780b) to acquire Ford (40b) or GM (44b) (with a friendly ftc); so for 15% of their shares, that could become the only "American" manufacturer - then they'd probably strip those 2 for parts, end the dealer model, bust the unions, maybe keep a few of the popular models.

Some of this might be inevitable anyway, as autos become more expensive (tariffs, inflation, chips, unions), and more reliable (dealer maintenance model, fewer sales)