If you need help with imagining this kind of person, take a look at a similar example. There is a known epidemic of sociopathy, racism, authoritarianism, and unnecessary violence in the American police. This is partially due to systemic factors, and partially because it attracts that kind of people. Yet the police are not, as a whole, required to kill people. If they do, it is a relatively rare, unfortunate eventuality which leaves many of them scarred for life. Most police officers never need to kill anyone, although they are aware of the possibility.
Imagine the state of the police if standard operating procedure was to either summarily execute all suspects, or to capture them for the end of torturing them into revealing information that will lead to more effective killing. Imagine if the police, in the pursuit of this duty, regularly killed innocent women and children and argued that this was unavoidable outcome. And imagine that this happens a hundred thousand times a year, and is the known and open procedure of the police.
What kind of people would be attracted to this position?
But this thought experiment is not strictly necessary. Evidence is a better proof than theory, and we have it in spades. The evidence indicates that members of the United States military are largely racist sociopaths. We see this in surveys of military members and their lack of likelihood to abhor murder, we have it in official testimony from former soldiers, we have it anecdotally in the stories that soldiers share when away from kept, embedded journalists, and we have it sprayed across the walls in the blood of tens of thousands of human beings.
We also see it in their arguments for their decision to join and remain in the military. The hunger to deliver punishment. The abdication of all personal moral responsibility to a code invented by others. The worship of weapons. The notion that their economic self-interest trumps all other considerations. The fact that they consider it unthinkable to accept negative consequences for their own decisions. Their nonchalance at murder, torture and manslaughter. And of course, open racism and bloodlust. Even when they complain, the pathological narcissism is palpable. They complain about their difficulty finding a job, about their insufficient medical care, about their mental illnesses, suicides and injuries, their dead and crippled friends and family. The concept of extending even a thought to the state of their more numerous victims whose similar problems are far more egregious does not even cross their minds.
Every single member of the military today signed up during a time of war. Every single one knew what they were getting into. We like to pretend that the military system creates these people, but like attracts like.
Yet of course the system they are attracted to does exacerbate the problem. To bring up the police again: while a very racist organization, blacks, hispanics and other minorities are represented in the ranks of police officers. There are no Iraqis or Afghanis in the ranks of the United States military, and a vanishingly small number of even Iraqi- or Afghani-Americans. There are no consequences for soldiers either. We know from testimonials that rules of engagement, such as they were, were considered a joke and soldiers regularly frame innocent murder victims when such events are not simply and explicitly swept under the rug by command. When police nonfatally beat Rodney King and got away with it, Los Angeles burned in outrage. When Marines went on a murder rampage in Haditha, killing 24 innocent people and defiling their corpses and got off scot-free, no one cared. When Calley and his men slaughtered 500 Vietnamese civilians, the only outrage was that he was punished too severely.
Society lets them get away with it with their worship and ceaseless apologism. The military is the most beloved institution in America, and troops are given constant praise from the entirety of the even relatively mainstream ideological spectrum from Michael Moore to Rush Limbaugh. We pretend that their sometimes difficult situations - situations that they put themselves in - make them worthy of respect in the absence of considerations of ethics. We thank them for their service without even so much as asking what service that might precisely be. We regurgitate grade-school cliches about their defending our freedom with no critical thought whatsoever and we make excuses based on theories of race and class background that lack any substantiation.
If you want a better world, you will not support the troops. You will look upon them with the contempt they so richly deserve, and remind yourself that their deaths and disfigurement at the hands of foreign fighters is the only mechanism ever demonstrated to have slowed the US war machine. A soldier committing suicide is not a tragedy; it is the closest thing that passes for justice in the world as it is.