Ignoring debt and actual enterprise values, the more important point is that any business valuation produced by comparing to market prices of other businesses is flawed at best.
Unless you are one if the few and nearly extinct economists who believe the stock market is perfectly efficient, comparing by market price often leads to justifying one mis-pricing by another mis-pricing.
For example, Yahoos ridiculous pricing during the bubble could always be justified by even more ridiculous prices for companies with near zero revenues by pointing out Yahoo had revenues and was growing them incredibly fast.
The only question you need to ask about Tesla is how can a $30B revenue company be worth a $680B valuation? How long before Tesla’s earnings catch up to the risk free returns on $680B (roughly $32B/year)?
Assuming an optimistic 15% after tax profit margin for the rest of its life, Tesla would have to grow revenues seven times. At 15% a year, revenues double ever 5 years. So in roughly 14 years Tesla would be reach an annual after tax profit of $32B. And it would still be $200B behind in total net profits, it takes nearly 20 years for Tesla to generate more total net profit than the risk free investment.
Is that reasonable? It all depends on the risk Tesla falls short, and whatever assumptions are in your DCF analysis. That’s a long time to catch up, I’m gonna go out on a limb and say far from a slam dunk.