I think this is like asking "Should Amazon be worth more than all e-tailers combined?" circa 2009. Both of their businesses are growing in tangential directions to their core business. In just about 5 years, AWS turned from some "nice supplemental income" to becoming the company's new core product.
The Tesla bulls are betting that Tesla's energy collection and storage products will grow to eclipse their car business and take advantage of the economy of scale of the GigaFactories. The bears are only looking at Tesla as a niche car company.
DHH had a widely shared post where he said FB wasn't worth $33B+ and it could never be. He was clearly wrong (off by an order of magnitude). Eventually there will be some overvalued companies (WeWork before the valuation plummeted might be a good example). But given how many bear predictions have turned out to be really wrong, it's good to be skeptical of similar arguments going forward (they won't always been wrong, but some have been spectacularly wrong).
Is there any real reason why Tesla should be worth more than the rest of the US auto industry combined? Can Uber ever actually turn enough profit to justify their valuation? At what point does Amazon stop growing and their PE ratio start mattering?
Right now investors seem to believe that these companies have a very bright future ahead of them. Some of these companies have had “a very bright future” for over 20 years now. Some of these companies have very bright futures even though they’re only supported by investors and have never made any money of their own. Uber, for example, lost $8.5b in 2019 and are surely going to lose a ton this year too.
In the long run, how many SV unicorns and traditional companies pretending they’re tech companies will actually prove their valuation was right? A bear would say very few.