Having experience with both business school and the military, it's also the fact that military guys have a few unique qualities that you develop that business school just doesn't develop.
1) lateral thinking for mission accomplishment. When you're in, you have to get a job done and you are almost always resource constrained. Tough shit, you still gotta figure it out, so you get creative and find non-obvious solutions.
2) an ability to get by with the bare minimum. Understaffed, undermanned, under-resourced, unclear direction, you are still expected to meet the mark with what you're given.
3) an ability to just suck it up and tolerate suffering.
4) ability to be flexible and reactive and change things on the fly. Lol we had the saying "Semper Gumby" in the Marines because more than half the time what you thought you were doing changed by mid morning and then changed again after lunch. Change was a constant so you learned to just stay flexible, roll with it, and do what needed doing in the moment.