They can only move up to a certain point. To make it to the senior enlisted ranks it is now proven very difficult without any college. To advance as a senior enlisted; you won't without a bachelors degree or higher. Very few are the excepiton, but no H.S. dropout will ever make First Sergeant or Command Sergeant Major.

To be an Officer it is a pre-requisite to have a college degree.

If H.S. was too much of a pain in the a$$ to them, do you really think they have what it takes to advance in the military? All of the standards for advancement both written and unwritten have changed since the Vietnam era.