Which works when the unit economics are good. You can take the profit from an operating business, and just inject it back in the business to grow. That sometimes looks like an unprofitable business, but the test is: "if the company freezes growth tomorrow" would it be profitable?

Teslas are profitable, once you pay off the amortized cost of a factory. It isn't clear that uber is profitable. They had 5-10% gross margins pre-IPO, and it has gone negative since.