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 infrastructure that was going to carry the traffic they would get
after their build out, meant that any cash crunch had this amazing multiplicative effect, which resulted in a massive implosion in practically no time (one customer I talked to in 1999 was putting the finishing touches on a $1.2M PO on Monday, and when we showed up for the meeting on Wednesday the doors were locked and the name of an attorney's office was there for questions. Later I found out they were negotiating additional funding and even though their business plan was "solid" once some other companies had gone under, everyone got too skittish to commit. They were already burning through cash to people who were putting in new fiber cables etc. They went upside down (more obligations than cash or revenue) on Tuesday and the bank sent the attorneys (and Sheriff) over to secure the assets before anyone could walk them out of the building that afternoon. Pilots have a term for crashes like this, its called "controlled flight into terrain" where basically right up until the last moment the pilot was flying the plane. So it can be with startups that right up until the day it isn't flying they are in control.
Its nice that if Uber does implode (not that they will) that only VC's will lose their money, of course Uber drivers will be out of their jobs as well but they hopefully won't be greatly finanically hurt. And of course a lot of employees that thought they were millionaires will realize that they aren't (been there, done that, got the t-shirt :-()
I hope at some point in the not too distant future we can get some more transparency on their financials. I really do consider them the poster child for the 'dynamic' economy (one where service suppliers and service demanders are paired in real time for a fee). If they can't make it work it will really call into question if it is even possible to make it work.