That's kind of the point. People (investors) think that in the not-so-distant future Tesla will be much bigger than Renault, and are extremely confident in this

That's kind of the point. People (investors) think that in the not-so-distant future Tesla will be much bigger than Renault, and are extremely confident in this. It doesn't really matter to investors where Tesla is right now except as a mechanism to build extrapolations. If you are extremely confident that in 10 years Tesla will be twice the size of Renault, then you need to buy buy buy right now before other people realize it. Renault's size isn't expected to change significantly over the next decade. Tesla's is. This means that if you own Tesla shares now, 10 years later they are going to be worth a massive amount because Tesla will be much bigger than Renault, so the price naturally rises to that expectation, only abetted by the possibility that Tesla collapses. It isn't about where the company is at the moment. It is about where you think the company will be in "the future" (at whatever point that is relevant to you) reduced by the probability that you think they will fail (and most people think that chance is tiny). So when Tesla starts making a profit, its market cap probably won't have grown that much, because it was expected behavior priced into today's valuation.