Exactly, the market isn't always rational. There's a lot of work on quantization in neural nets, for example, that can allow them to work sufficiently well on less capable hardware. It could be that some breakthrough there would obviate the need for NVDA hardware (or at least reduce how many are needed).
It is rational if you interpret market capitalization and share price movements as “the market is saying Tesla WILL be worth more than x,y z combined between time now and time whenever you want to sell it.”
For different people, the timespan between now and when they may want or need to sell it is different, and thus different people will arrive at different conclusions.
And note that “worth more” above simply means growth in market capitalization, so as long as someone is willing to buy the shares at a price supporting that increased market cap, then it does not matter if Tesla is still selling fewer cars than the others combined.
