When you consider that the vast majority of "volunteers" in our army come from the lower socio-economic ranks of our country, do you really believe it is a totally "volunteer" army? Why aren't there more sons and daughters of the upper middle class and higher groups volunteering? I'm sure they believe in noble causes, patriotism, etc. as much as anyone else...
It just isn't so black and white...
You mean people like Pat Tillman?--someone who gave up wealth and prestige in order to serve his country and sacrifice his life defending that which he believed in. And are you suggesting that any US citizen is FORCED into the military. Maybe a few are given a court ordered ultimatum to join (if they got in legal trouble), but thats about it. The reason for the disparity in socio-economics ranks within the military is simply because those on the lower rungs have fewer options for career paths, whereas those higher have things like college, trust funds, and high-earning civilian jobs available at their fingertips.
It'd be like wondering why you don't see any doctor's or lawyer's kids working at Burger King. Quite simply, they feel like they can do better or be more productive doing something else.