The mistake you're making in your analogy is comparing a group of people to a single person. ISIS is not one united front, and most of the people who actually fight -- not the leaders making videos, but the people doing the killing -- do so for much less grandiose reasons.

Casting the rise of ISIS as a black-and-white, good-vs.-evil struggle allows some very clever politicians to have their way: torture some folks, spy on citizens. But if we look deeper at the situation, we'll see that motivations are more complex. In doing so, however, we (the West) must confront our role in the situation.

"For the first time since he came into the room he smiles—in surprise—and finally tells us what really motivated him, without any prompting. He knows there is an American in the room, and can perhaps guess, from his demeanor and his questions, that this American is ex-military, and directs his “question,” in the form of an enraged statement, straight at him. “The Americans came,” he said. “They took away Saddam, but they also took away our security. I didn’t like Saddam, we were starving then, but at least we didn’t have war. When you came here, the civil war started.” [0]

[0]http://www.thenation.com/article/what-i-discovered-from-inte...