Well, they currently sell far more passenger electric vehicles than every other auto maker combined, and demand only seems to be increasing even as production continues to increase exponentially. Many countries and US states have gasoline car bans set to take effect in the coming decades; if the incumbent manufacturers continue to lag behind Tesla as badly as they've done so far, it would seem Tesla is poised to eat a lot of other car companies for lunch.

That alone still might not justify the current valuation, but then you add in their solar panels, solar roof tiles, stationary storage, and other things in the pipeline like insurance, renting out their EV charging network, possible AI applications and/or software licensing, etc. etc., and the valuation seems at least plausible to me.