That's unfortunately what war has been for most of human history, and still is in some parts of the world. Today in developed and democratic countries, soldiers are in most ways like any other kind of employee in the public sector; they get paid decently or even well and the state, which is answerable to civilians who care about human life even if it's on the 'other' side, has extensive power to punish them if they break the rules. In times like the Thirty Years War, you often even need to let your soldiers loot, rape, and pillage just to keep your army intact; that is how you're repaying them for risking their lives for your cause.