Most of the people I've known and worked with in the military never had to kill anyone.
[1] http://www.af.mil/News/ArticleDisplay/tabid/223/Article/4678...
[2] http://www.af.mil/News/ArticleDisplay/tabid/223/Article/4667...
Your friends may never have killed anyone directly, but they have certainly assisted in it. For every supply trip to Haiti, there are thousands of supply trips moving weapons and soldiers around the world.
But if you don't want to contribute to anything that could be used to kill people, you are severely limited. Anything from open-source code (Linux comes to mind) to chip design can be used to kill people. Remote control airplane hobbyist? If you have a breakthrough on your hobby, it can presumably be used in drone technology.
"For every supply trip to Haiti, there are thousands of supply trips moving weapons and soldiers around the world." What's wrong with that? We have soldiers on the ground in lots of places. In a lot of ways, that's probably a good thing. The 2011 involvement in Libya, for instance, is generally viewed as a responsible intervention of US military.
I personally don't see joining the military as fundamentally more supportive of its actions (conceptually) than being a normal (US?) citizen who isn't politically involved in reduced military action. Sitting back and just working in our economy also indirectly supports the military, and doesn't make you any more moral (or less culpable in our military's actions) than someone who joins the marines. Likewise, what if you do join the military but vote against (and otherwise support) any and all people involved in reducing foreign military action?
I appreciate how this sounds, but think its a point worth discussing given the moral implications (blame) of your statements.
Yes, a lot, maybe even most people that enroll in the military eventually leave without ever having seen combat, action, or any situation in which they were asked to kill another person, but there is no way to enroll in the military with the assurance that you'll never be asked to perform that duty.
Coast Guard, at this point, is not only not guaranteeable to avoid action, but should they see action, it's not unforeseeable that it would be against American citizens.
But in general, military service needs to be more than just pragmatic. You are going to be called into areas to either kill or help people being killed. Either way that's a lot more psychologically speaking than going to pilot school.
And having people trying to kill you is probably a deal breaker for even more people.