1. The regulations that Uber skirted around and then loosened up to provide more drivers can also be used by other companies. The gates are open, but not only to Uber.

2. Drivers and customers are fickle. My market used to be mostly Uber and is now mostly Lyft because all the drivers hate Uber. When Uber and Lyft run out of cash to blow on subsidies, they don't really have much of a selling point.

The problem with Uber's business model is that the main cost is the driver, who is not going to go anywhere anytime soon. It's no Amazon, where they have efficiencies of scale in logistics, datacenters, etc.; you don't get economies of scale by being bigger in the taxi business. It seems more like Moviepass.