I think your argument is missing GP's point entirely. The point was that a functioning market economy would evolve so that companies that sell products or servi

I think your argument is missing GP's point entirely. The point was that a functioning market economy would evolve so that companies that sell products or services at a self-sustaining price survive, whereas companies that lose money continuously die. However, this is clearly not the case, given that companies like Uber, as you mention, do survive without being profitable at all. Competitors that are not backed by near-infinite money cannot survive this competition, regardless of their product or efficiency. Whether or not a functioning market economy could ever exist in reality if of course another question.