The fact TSLA is valued more then all the auto manufactures combined is absurd. You're naive to think big auto is just going to sit on the sidelines. Big auto has the infrastructure and production lines to mass produce fully electric vehicles for a fraction of the cost of a TSLA, something TSLA will never be able do. Ford is already leading the charge with the F-150 Lightning and converting old factories into fully electric vehicle production plants. TSLA is just as overhyped as Elon Musk.
Tesla has immense future potential. With fossil fuel reserves are depleting fast and the price is becoming unreasonably high for the car owners, Electric cars are the answer to all these problems. Tesla has not yet started marketing or selling their cars to every country in the world. But a time will come when Tesla will try to penetrate the majority of the countries with their electric cars.
I believe that Tesla stock is still undervalued considering the future potential it has. This downfall is temporary just like bitcoin.
What you're saying is true, only you've forgotten about, perhaps, the most crucial part in any business - competitors. Though we have to admit, Musk definitely has a name and his word means a lot, this, however, doesn't exclude cars like Nissan Leaf, Chevy Bolt or EV by Volkswagen.
Having Tesla is prestigious, but it is also pretty expensive, so many people can prefer other models over Tesla if their true intentions are to care for the environment and not the show-off.