Just a couple of nice kids, marijuana-smoking, beer swelling layabouts. Who would have thought they would go to Iraq to murder people they never had never set eyes on before?
I think the psychology of it is guilty conscience. These kids know that Muslims aren't supposed to drink alchohol.
So they start feeling guilty and useless. So they resolve to square their consciences by blowing up infidels.
Very much like the psychology of liberals. Deep down, they know it's wrong to do some of the things they do. So they absolve their consciences by raising other people's taxes or undermining their country.
I think it's more of a romantic idea for them--a triumphant return to the homeland where they will fight the New Crusade and drive the infidel from the Land of Mohammed.
Or some sh!t like that.