Why Did Snapchat Turn Down Three Billion Dollars?

Matt Buchanan suggests the better question than “why did snapchat turn down 3 billion dollars?!?!” is “how did attention become so valuable?” While snapchat is clearly a major phenomenon, is it going to be so valuable? And when countless social networks have just evaporated into ghost towns, will snapchat be valuable before their notoriously capricious demographic simply moves on to the next thing?