To suppose that the value of a common stock is determined purely by a corporation's earnings discounted by the relevant interest rates and adjusted for the marginal tax rate is to forget that people have burned witches, gone to war on a whim, risen to the defense of Joseph Stalin and believed Orson Welles when he told them over the radio that the Martians had landed.
It is no exaggeration to say that since the 1980s, much of the global financial sector has become criminalised, creating an industry culture that tolerates or even encourages systematic fraud. The behaviour that caused the mortgage bubble and financial crisis of 2008 was a natural outcome and continuation of this pattern, rather than some kind of economic accident.