To answer your op question.
Whether serving at home, abroad or fighting and dying in foreign countries feels like a direct contribution to your "freedom" is inconsequential. Each of the servicemember swore an oath at least once to defend the constitution in any circumstances, giving up their personal constitutional rights in some respect with the purpose of serving as a small percentage of citizenry does so the majority of Americans do not have to.
If the people in control misuse these men and women through political, financial, personal or more nefarious motivation, it is not on the men and women they are using, the blame or shame.
When you are called, you go. When you are standing over IED placed on the road, wondering WTF is your next step and how are you going to move forward, you certainly aren't thinking about the cunts that sent you there or if 9/11 was an inside job.
The best explanation I can give is to attempt to quote the Brian Bana character "Hoot" from Blackhawk Down.
When asked why he did it and if he was some kind of war junkie? His response was "It ain't about that. It's all about the guy to the left and the guy to the right of you."