Substitute “investment banks” for “Rome” in the following quote from Edward Gibbon’s History of the Decline and Fall of the Roman Empire and it gives you a pretty good analysis of what has gone wrong with the industry.

"The decline of Rome was the natural and inevitable effect of immoderate greatness. Prosperity ripened the principle of decay; the causes of destruction multiplied with the extent of conquest; and as soon as time or accident had removed the artificial supports, the stupendous fabric yielded to the pressure of its own weight."