The problem with the "unicorns" in the private market is that its getting funded size wise as if it's a publicly traded company. Ubers 40Billion valuation isn't based on it's funding not on it's actual performance (400million revenue, 400million spend).

As long as a private company can getting to the next round of funding it doesn't matter if it's actually even close to becoming a sustainable business. So you can basically keep extending a "false" business in that all you need is convince someone to believe you can become even bigger than you already are, but without showing it through your actual revenue.

As a publicly traded company this wouldn't ever work. Amazon isn't making a profit but it keeps growing revenue wise (for now) if that somehow stops then it will get hit too.

At least thats my take on it.