Digging Into the Meltdown

DIGGING INTO THE MELTDOWN....Tyler Cowen notes Europe's disastrous exposure to emerging market debt and says:

By the way, this is further evidence that the driving force behind the earlier boom was the global savings glut, and sheer giddiness, not the excessively loose monetary policy of Greenspan's Fed.

But why not both? And a few other things as well, including the increasing concentration of income and wealth in the hands of the rich? Are they really all mutually exclusive?