Not military, but in civilian life one of the engineers I worked with started his working life as a shearer before becoming a technical assistant - almost the lowest of the low, just above clerical assistant. When he saw how much better it was to be an engineer, he did his Matric at night & topped the state in maths, then went to uni and did a M. Eng.
As BPF says, he was wise to all the scams, but he also knew when counselling and mentorship rather than discipline was called for. Also, some senior engineers realised that it was wise to listen to him, especially when it came to dealing with farmers. (We were in the water industry.)
But, as others have said, it depends entirely on the person. I reckon if he'd gone straight from High School to uni he'd still be the much same person.