There is literally no way for a mass-market taxi service to make money unless they have a monopoly, or some unexpected disruptive technology comes along that gives one company an unassailable advantage in lowering costs. The Uber app was the original innovation, but it's not particularly innovative anymore. Besides Lyft, traditional taxi companies have similar apps in some markets. Skirting regulation and good labor…
UBER won't be a monopoly. But UBER and Lyft could offer lower costs than taxis, because of cheap labor, no medalions, and less empty rides they could offer their drivers. So it's basically a UBER/Lyft duopoly, after the growing phase. And Duopolies are good businesses to be in.
You forget that dispatcher already take a pretty big cut already and I don't know where you live, but here in Montreal, we have a bunch of them that are all profitable. Sure dispatcher started to makes apps, but they only cover a tiny market (thus the apps is more expensive to develop per ride than Uber) and plenty of their clients prefer calling, thus an human operator (which Uber doesn't has to pay for).
Our government also decided a few years ago to force them to accept credit/debit card. One of my friend worked for one of the operator that rented terminal to taxis. They were profitable too.
If Uber can't make money by being much more efficient in MULTIPLE already profitable business and that's WORLDWIDE, there's something pretty wrong.