A snippet from the "Cost of Conflict in the Middle East," a report (pdf) by the Strategic Foresight Group:The countries in the Middle East that are directly involved in or affected by the Israeli-Palestinian conflict, internal strife in Lebanon and the U.S. invasion of Iraq have lost a whopping $12 trillion dollars (in 2006 dollar value) in opportunity costs from 1991 to 2010. 

Grunstein comments:

I'm not sure if the vision of how things could be is enough to get people to come to their senses. But the fact that the Middle East is not a prosperous global power center is one of the most prominent and enduring testaments to human irrationality that I can think of.