Because here's the thing―we don't give a shit about fairness here. We're soldiers. Soldiers do not give the other guy a sporting chance. Soldiers shoot in the back, lay traps and ambushes, lie to the enemy and outnumber the other bastard every chance they get. Your kind of murder only works among civilians. And you were too cocky, too stupid, too insane to realize it.
The excerpt emphasizes the ruthless nature of soldiers, contrasting their actions with those of civilians. It suggests that the realities of warfare are devoid of notions like fairness; instead, soldiers must employ tactics that ensure victory by any means necessary, such as ambushes and deception. This perspective highlights a pragmatic understanding of conflict where moral considerations are secondary to survival and success.
The speaker criticizes an enemy for underestimating the brutality of war by naively clinging to a sense of honor. It implies that the enemy's attitude is a liability, as it ignores the strategic mindset required in combat situations. Ultimately, the passage reflects a harsh truth about the moral complexities of warfare, where the rules of engagement differ vastly from those in civilian life.