Then you're missing the point. Historically, the kind of people who start wars of conquest tend to hold philosophies that value only their own in-group and its associated resources. When you don't value the happiness or prosperity of your victims it's quite easy to "win" a war. You just have to make sure the cost isn't so astronomical that it wipes out the benifits your in-group can reap by exploiting your victims over the next few generations.