As I often have on this blog, I cannot strongly enough endorse The Looming Tower, given to me originally by Res Ipsa the best book I've ever read on Al Qaeda and the systemic nature of how extremists groups like it operate (the great movie from Germany the Beider Meinhoff Complex touches on this subject as well) -- generally these folks who threaten items in the West are not the folks living the war zones. No, they are often the wealthy dilettante children of Egypt or Saudi Arabia. They have enough knowledge of western culture to like some of its values, yet resentful of some karmic spiritual death of their own culture as they perceive it, leading to some sort of aesthetic resentment requiring violence.
The middle and upper classes have historically been the places to look for revolutionaries and extremists -- and, of course, blog posters and blog readers. Not the poor, they are too busy trying to get by day-to-day to have time to be reflective about destroying shit. Just go down the line, our own revolutionary heroes, Robespierre & company, Marx & Engels, Lenin, Trotsky, the Red Brigade, Mao, Ho Chi Minh, Pol Pot. Some heroes, some scoundrels, some in betweens, but all uniquely upper middle to wealthy classed. Situation is no different in the Middle East -- except of course for the possibility of success being less, while the potency of the individual destructive act being increased. What could be done to Alexander III, McKinley, or Franz Ferdinand on a limited basis, can no longer be easily done to them but a more widespread mass killing of civilians is out there.
It might be nice if some of our more pervasive media outlets reported on this sort of phenomena and how seemingly timeless it is, rather than talk inextricably about broad sweeping generalizations.