Even if you assume tesla is only making cars (they're doing more than that), why is no one asking why existing car companies are making so little? Why is apple worth $2 trillion based on a phone, while car manufacturers making something even more valuable than a phone, are only ~25% of that combined (excluding Tesla)? It's because traditional car companies are terrible at capturing the value they create. They're wasting a ton of money on expensive ads competing with each other. They outsource their entire supply chain, giving profit away to suppliers. They have dealer networks they are beholden to which eats into their margins. They don't upsell high-margin software add-ons to existing customers. They innovate slowly and reluctantly. Companies that aren't good at turning a profit don't tend to be worth much.
When was the last time you saw a Tesla ad on TV? When was the last time you saw Toyota or Ford sell a $7,000 driver assist upgrade or a $2,000 speed upgrade (both delivered over-the-air and instantly)? When was the last time you saw a Tesla dealer and not a store where you just go buy a Tesla like an iPhone? Tesla has the chance to dominate the car the way Apple dominates the smartphone and capture an enormous amount of value in the process, way more than any traditional car company has been able to.