As others point out this isn't necessarily bad, but it does mean that Uber is extremely vulnerable. If we learned anything in the last bubble it was that attempting to bootstrap through the power curve is exceptionally susceptible to capital constraints. Back in the dot com days a number of 'baby telephone companies' that were building out their networks and spending huge amounts of money on laying out the infrastruc…
The question is whether Uber is buying anything of durable value with their billions. Dot-com companies were buying warehouse space, laying fiber, creating lock-in. Uber might be running competitors out of business, but it's a business with low barriers to entry, and they're not really locking in customers or drivers. They may claim to be building a moat, but to me it looks more like they're buying overpriced water.
Google search changed that, over time it became easier to find a phone number online than it was in the books. Then with the smart phone it combined both the phone and the number database (search engine) into a single device and now very few people use phone books.
But that habit changed slowly, over a decade at least to go from early adopters to the majority of people out there using their phone (or the web) to look up numbers. So the habit for calling a cab is changing slowly. From regulated livery service to less regulated ride share service. During that transition Uber is apparently "spending" billions[1] to connect in peoples brains 'Uber' and 'rideshare' so that as ride sharing becomes the expected norm, people will think of it as Uber not "any number of ride share companies."
[1] It is an odd definition of spend, they are perhaps purposely under pricing their service (so subsidizing) in order to encourage use.