Some mass murderers murder masses because they enjoy murdering. The act itself is the reward.
There are certainly those feel-good endorphins one gets from crushing one's enemies, seeing them driven before you, and hearing the lamentation of their significant others. Or knowing that you did your small part in wiping out (insert scapegoat here) who (insert trigger for ancient, vague, and probably overblown vendetta here), while making what was once theirs (but really should have been yours) yours.
All that free rapine is likely a mighty incentive for one's horny near-child (pretty much anyone below age 25-30) soldiers as well, especially if you tell them that everyone will be better off with the next generation being their descendants rather than the descendents of (insert dehumanized enemy here), or at least that what happens in Vegas stays in Vegas.
Of course, some people just get off on that ultra nationalism sports team fanboi crap and will enjoy anything as long as you tell them it's to make (insert favorite Gatorade color and/or arbitrary geopolitical boundary here) great again. I have actually met people who have subsequently died serving in their country without being able to find it on a globe or even knowing the
millennia it was founded.
Murder/war was so much more honest when you didn't even need a pretence beyond killing people and taking their stuff, or that you credibly believed they may do the same to you. Now it's just got so much fluff wrapped around it that some people never see it for what it is...not that I'd expect them to stop, but at least the grunts would be demanding their fair share of spoils rather than accepting payment in misplaced duty, while those who will never be at risk from violence make a living and a killing through it.
Anyway, I've digressed long enough for one post...
But the most obvious scenario is of course war. Elite could do with a Fed vs Imp war.
The game has plenty of wars happening all the time. What we really need is the ability to join in-game minor factions in some more apparent way.