Gambetta and Hertog suggest that this mindset combines with frustrated expectations in many Middle Eastern and North African countries (PDF), and among many migrant populations, where people with engineering backgrounds have difficulty in realizing their ambitions for good and socially valued jobs. This explains why there are relatively few radical Islamists with engineering backgrounds in Saudi Arabia (where they can easily find good employment) and why engineers were more prone to become left-wing radicals in Turkey and Iran.
Some people might argue that terrorist groups want to recruit engineers because engineers have valuable technical skills that might be helpful, such as in making bombs. This seems plausible – but it doesn't seem to be true. Terrorist organizations don't seem to recruit people because of their technical skills, but because they seem trustworthy and they don't actually need many people with engineering skills. "Bomb-making and the technical stuff that is done in most groups is performed by very few people (PDF), so you don't need, if you have a large group, 40 or 50 percent engineers," says Hertog. "You just need a few guys to put together the bombs. So the scale of the overrepresentation, especially in the larger groups is not easily explained."