That's not really a valid response and I think you know it. There are huge numbers of third-worlders who don't engage in this type of violence. If what many Islam apologists say is true and there aren't that many Islamic terrorists, then the fact that many terrorists in the news
aren't poor undermines your theory.
Of course it's a valid response.
The Middle East is not Third World like most of sub-Saharan Africa. Have you been to the Middle East and sub-Saharan Africa? Sub-Saharan Africa largely doesn't even have the technological infrastructure that would allow Al-Qaeda's or whatever terrorist group du jour's messages to be disseminated. There are huge numbers of poor people in the United States who don't commit crimes, either, but who commits most crime in America?
Sure, a few terrorists are physicians. Most of the leadership of these crazy groups are well-educated and well-off. But look at the majority of the foot soldiers, err, suicide bombers. They're underemployed males in the prime of life. They become terrorists because they have nothing to lose.
How familiar are you with the history of the Muslim world? I'm certainly not going to make the argument that Islam is the religion of peace, but until the rise of global-scale oil exploitation, Muslims were no more or less violent than Christians and Jews, the other monotheistics religions (which are comparatively more violent than other religions). You've heard of the Crusades, yes?
Islam is
not the reason brown people are blowing shit up in the white man's back yard. Having no economic hope and having no voice drive people to criminality. Having God's blessings makes it easier to commit increasingly heinous crimes.