It's a complicated mess that's easy to generalize. Why people join the military, and what happens to them when they get there. In the end it comes down to which culture has more people in command and people willing to follow.
One of the most stable and predictable and safe methods of escaping poverty in the USA is policing or nursing or firefighters etc. I hate all cops, I'm from the ghetto, but I understand why some poor kids sign up for it and while I do blame them I can't say they had a choice, not really.
Also the military isn't a long term career for most people. If you're enlisted, it's a pretty fixed term, and if you aim towards long term as an NCO or senior enlisted, there's a huge sink-or-swim culture that pushes out people not meeting standards.
I grew up in a rural area and went to a small school. The military recruiters hounded us. They were at our school all the time, called me first thing in the morning every day off I had (when I just wanted to sleep in) and absolutely pushed seeing the world and free college talking points to us.
