In this situation I don't think it really matters. If the VC money stopped, Uber would either go out of business or shrink back down to being a taxi company, in

In this situation I don't think it really matters. If the VC money stopped, Uber would either go out of business or shrink back down to being a taxi company, in which case they have no competitive advantage and no network effects, making switching costs extremely low. Being a more profitable taxi company doesn't mean much when most of your employees are also employees of your competitors, and most of your customers are also customers of your competitors. There's just no lock-in.