http://en.wikipedia.org/wiki/Market_failureSometimes, the market does not figure it out... especially with a populace that is imperfectly educated (and not "perfectly logical, perfectly rational" beings in most theoretical economics)
But even with perfectly logical and perfectly rational beings however, there still are market failures. And it is up to the population to create Governments to deal with these market failures. (Usually through deregulation or regulation)
Case in point: LEXG, a 2010 stock that is widely considered "pump and dump". Despite all the regulations, and centuries of knowledge of pump and dump... it still happened.
BTC itself has a growing volume of trade... but a lot of smaller cryptocurrenies are simply pump-and-dump schemes.