Well, I do think it has more to do with what someone else said earlier... the military is a common outlet for young people who can't get or don't desire to go to college and continue their education. I come from a military family and am the youngest (and first) Marine and I was pretty amazed at the sheer amount of men and women who enlisted because they come from very poor, small towns (one of my closest friends had never even seen a black person or an escalator in real life before joining the Corps); or they married early and hadn't had any better jobs where they came from; or they were unwed mothers at the age of 18, etc. Many different scenarios, many different stories. All culminating to the fact that they basically had nowhere else to go, or nothing else to do.
I did recruiting for a grand total of 1 month. And I called my command and asked them to get me back to my unit... why? because I saw exactly how recruiters get people to sign up. The exaggerate, they go to mostly black or hispanic high schools, they go to the malls in the poorer areas of town, and/or they just flat out lie to kids.
The college eduacted kids are usually the ones with a very clear picture of what they want out of life and the military and how to acheive it. They are mostly officers. There simply aren't alot of (in my own experience) enlisted men and women who start out their time in the service with a college education.