It isn't. I took a look in '95 at a 'cross-section' of the mid-career Captains and Majors leaving in the '90s up till then. These are the guys who will face the toughest transition to civ employment--y'know, middle managers, midcareer--like right now....
Chemists, Engineers of all disciplines, JAG Lawyers, Docs, Physicists... Anyone with a technical or science-type degree was bailing.
Staying: History, English, (Language) Majors, and a whole heckuvalot of 'Russian Studies' guys.
I had a running joke with some of the other LT's--when you ran across a Major bucking to make LTC who was zealously pushing the Clinton 'Consideration of Others', Operations Other than War', and 'Don't ask--Smoke Pole' doctrines, I would ask them: "Hey sir, you Majored in Russian Studies didn't you?" more times than not, I was correct....