Because it's not real money, most of it is just bitcoins that got converted to ethereum that got converted to coin dejur. Can you cash it out in small quantities sure, but unless something tangible comes of it you have nothing but worthless tokens.
I think that is key. It's similar to the .com boom (and bust) in the early 2000s. You had lots of examples where super-inflated company A bought company B, and paid for it with their super inflated stock. While the "values" reported won and lost where in the billions (trillions?), the fact is that relatively little of it was actually converted back and forth to real dollars.
