Any excuse will do

Read the “Background on Mohammed Reza Taheri-azar” from Terrorism Unveiled:

The guy I spoke with also said he seemed to have few friends and didn't "fit-in" socially. From this and his actions, Taheri-azar fits well as a "lone wolf" actors that go out and try to do the "will of Allah." Socially awkward and looking for something to legitimize themselves, to make them feel "worth" something---they turn to this type of behavior.

They find a purpose in a religious ideology because they are empty. He had money, he had an education from one of the finest schools in the country [I am biased], he had a job (although it was at a local fast food restaurant--Jimmy John's subs) he turned to this. Once again, this shows that it's not necessarily poverty that drives people to take on these type of causes.

Then review some assorted quotes from Eric Hoffer’s “The True Believer” such as this one:

"Passionate hatred can give meaning and purpose to an empty life. Thus people haunted by the purposelessness of their lives try to find a new content not only by dedicating themselves to a holy cause but also by nursing a fanatical grievance."

Those grievances can include – but are not limited to – Danish cartoons, Burger King ice creams cones, and Dutch documentaries.