The following two articles both place a lot of emphasis on a romantic attraction to war as an adventure, as captured by a reference to a TE Lawrence quote: “All men dream, but not equally.Those who dream by night in the dusty recesses of their minds, wake in the day to find that it was vanity: but the dreamers of the day are dangerous men, for they may act upon their dreams with open eyes, to make them possible.”
“Yet inexplicable as it may seem to many, the mere thrill of combat is often the primary motivating factor. While ideological reasons are cited in justification, the real reason many individuals travel abroad to fight is an age old search of adventure. This more than anything may have played its part in luring westerners to the Kurdish cause, just as others before them went to Bosnia or Rhodesia. The difference being, this time the war against ISIL provides a useful pretext for their actions.”
http://www.aljazeera.com/indepth/opinion/2014/11/very-secular-jihad-201411257617424922.html
“Would [these Western volunteers] fight in the Middle East if they were content at home? I don’t think the temptation would be very strong. For each person who goes there must be personal reasons – perhaps religion, perhaps some deeply held political conviction like the foreign volunteers who fought in the Spanish Civil War. That said, there is probably a sprinkling of pure adventurers – the kind of people who might otherwise become mercenaries.”
http://www.aljazeera.com/indepth/features/2014/04/white-saviours-arabs-syria-libya-201442145225666272.html
IR Theory & Practice 