You need to learn some basic finance. I read the article you posted:
"Uber has traditionally been tight-lipped about its finances, but a new leaked document, obtained by Gawker's Sam Biddle, suggests the $50 billion company is wildly unprofitable."
You are somehow assuming that a networth of $50 Billion dollars equates to cash-flow. My highlight of $50 Billion does not state anything about what that $50 Billion is. Is it revenue, profit, estimated worth? It is, as you will see, likely estimated net worth, which means that a company can still lose money on its operations. It's like me saying I live in a $2 Million dollar house, but I lost my job and am not bringing in any money to support my day-to-day living.
Proof of what I asset above comes from many other quotes in the article, which include:
"Uber's net revenue in the first and second quarters of 2013 was a combined $32 million, according to the document, and its numbers for the second half of the year were about $72 million, bringing its 2013 annual revenue to $104 million in total.
In this case, Uber's net revenue is the amount the company keeps from each ride, not how much each ride actually costs with the driver's cut in it.
In the first and second quarters of 2014, the documents show Uber generating about $102 million, nearly as much as the entire year prior.
Gawker's documents also show that while the company's revenue has been growing quarter over quarter, its losses are also increasing. Its losses in 2012, according to Biddle, totaled $20.4 million. In the first half of 2013 the company lost more than $15 million."
So that's how a $50 Billion company loses money.
And keep in mind, it's only worth $50 Billion when someone actually pays $50 billion for it.