My wife's grandfather did almost exactly this: navy pilot (I forget the exact details but he had at least one of those "firsts" like "landing on an aircraft car

My wife's grandfather did almost exactly this: navy pilot (I forget the exact details but he had at least one of those "firsts" like "landing on an aircraft carrier at night"), survived WWII, got out, was a teacher for 20+ years, and developed a keen interest in equities at exactly the right period for that. As I understand it, the flipside of this was that not very many people in his (very early) cohort survived, in case someone is thinking of this as "easy government money".