So I guess “stocks like Tesla” are really just tulip petals? What are people paying for?

It's a great question. Future potential, leadership, tech stack, manufacturing capacity, etc. There is a lot of "soft" aspects of running a company and valuation is one of the most difficult/error-prone things to do.

Damodaran's Google talk kind of does a good job describing valuation of high-growth companies (it is deceivingly simple): https://www.youtube.com/watch?v=Z5chrxMuBoo

> it can continue to moon indefinitely if the market dictates it

Not really. The higher the price gets, the more new money it takes to move the price higher. TSLA has done significantly worse than the overall US stock market this year.