My idea about this is that there is no way to know which individual Islamists will turn to terrorism. We cannot, in my view, say that poverty drives this because there are very many examples of people becoming terrorists even though they did not grow up poor. We cannot say that their religion drives them to it because there are millions of people who believe strongly in Islam and yet do not become terrorists. Therefore, it must be personal traits that make people become terrorists.
To be sure, there is something about Islam as it is practiced in many countries that makes people willing to become what we would call terrorists. (For example, I am calling anyone who would go to join ISIS a terrorist even though the majority of ISIS members fight more as soldiers and do not commit the atrocities we see on the news.) Some Muslim leaders preach a religion that does condone violence even if most Muslims do not think that is Islam’s true teaching. So, religion does push some people towards terrorism.
I think that a feeling of grievance pushes people towards terrorism as well. Many Islamists feel that the West has oppressed Muslims over the years. They feel that the problems of their countries have been caused by the West. By colonizing Muslim lands and by engaging in things like the wars in Iraq and Afghanistan, they say, the West has waged a war against Muslims. Therefore, they feel angry and willing to become terrorists.
However, neither of these factors can explain why any particular Muslim becomes a terrorist. Too many people who are Muslim and who feel aggrieved do not engage in terrorism. The reasons why any individual becomes a terrorist must be rooted in their personal circumstances and their specific personality. This means that we cannot predict which individuals will become terrorists.
I think this type of activity has two motivations. One is humans need to be in a group where they feel attached to. Two humans learn better when they begin an activity they like or feel a part of when they are young. With these two motivations recruits in existing or new endeavors makes it easier to pursue destructive or constructive life goals.