Hmm, doesn't this all smell very familiar? All of these young men who want to go overseas and kill infidels and make their names ... sounds like a Crusade without a cross. (Crux being the Latin root word of that term).
Sounds like boys being boys to me. A particular percentage trying to find some cause. Their just out on the "three or so" standard deviation groups in their passion.
The one standard deviation groups usually have less extreme causes, like how often you can get laid, get pissed, riot at out of control parties, lay rubber in front of peoples houses in the middle of the night.
On the opposite side of the distribution are the ones trying to save the whales, save the sharks, save the forest, save the cockroach.