The term "military service" itself irks me to no end. It's not service, it's a government job. No one thanks DMV employees for their "service".
My husband is a career sailor, in his 3rd enlistment, Iraq war veteran, and he takes more of a "it's a job" look at it. He still doesn't really know how to respond to strangers' "thank you for your service" even after 14 years.
I think people say it because they respect someone's willingness to risk their life. Especially since we are taught that the military defends our freedom.
The OP quote was: "Soldiers fight for their own people but untimately [sic] end up killing other HUMANS."
I'm assuming the word was "ultimately", which is incorrect. Not all soldiers ultimately end up killing.
The statement was wrong and offensive. I will not apologize for getting in OP's chili about it.
You personally aren't on the hook for this. You signed up for the military, took oaths to defend us (for which I am very grateful) and took orders from decision makers who may or may not have been influenced in their decisions to do the right thing. The rest of us have a right to voice those concerns and ask hard questions about the opportunity cost of warfare. That doesn't mean we're questioning the concept of chain of command.
I hope our sons and daughters end up living in a world where risk is still ever present, but it is used for exploration and the furtherment of humanity, instead of fighting and killing each other over what will later be considered less important matters.
Edit for fellow HNers: Voting down a soldier for expressing some emotion isn't cool. You don't have to apply (misweighted) negative karma to someone who is sharing an important experience of their life to make an impact in the conversation. +1 on the parent - listen to your fellow man, no matter what he is saying.