I think a 10s of billion dollars of valuation are based on the current climate of governmental support from all major countries with the largest car market and the demand for such cars.I somehow have a feeling they base their valuation on capital already raised. So they already eating 10bln investment. Those investors need a certain return: 5x - 10x. (so let's pick a random number between these 8). So the 80bln. Nothing to do with how many cars they sold
I think people forgot that back in 2012, it was a question if people actually wanted electric cars or not and how big that market would be. Deadlines for the end of ICE era were not set back then, while a lot of major countries have set today in additional to severe carbon penalty for companies subjecting to EV credit penalties. This is most likely the reason why no EV companies IPO for what Tesla Ipoed at even without revenue.
So Tesla paved the way and answered a lot of uncertainties. These questions below were very much debatable and heavily leaned toward NO a decade ago. Remember the higher the uncertainty, the higher the return(also higher the risk).
1. Can electric cars be profitable? YES
2. Is there a demand for electric cars? YES
3. Is the government helping the push toward EVs? YES
4. Is climate change really a big deal? Yes because everything is on fire or flooded.