It's easy for a group of people to convince themselves that (using the example above) eliminating that one guy and taking his farm over there is a good thing, cause more people would benefit than would suffer cause we'd spread the wealth of that farm around, and that guy is a dick anyway. So yea, there's no good reason not to do it. Meanwhile, you've completely ignored the fact that maybe he's not so bad, you just let your greed get in the way of objectively evaluating him. And the reason you want his farm is because he's smart enough to figure out a way to get a better yield. So sure, kill him, but no one is left that understands how he got that higher yield, and now that you've killed one guy, it's not big leap to kill another, and another and another, again, all in the name of good intentions. That's authority for you.