> not charging you enough to cover their own costs

Are you an Uber employee revealing private information? If not, it seems you're making a big assumption about the proportion of their expenses that are marketing and growth versus steady-state marginal cost.

Amazon didn't make profit for a while and everyone wondered if they could. Oh, it's a low margin business, they'll never be profitable, blah, blah. Turns out they can, in fact, make a bit of money. Maybe Uber and Lyft can, too. Delta can, even though flights are a commodity business.