Why do officers choose to leave the Navy? I've never had a humble opinion, because anybody who knows me knows that I am not humble, but I'll give it a try just this once.
I think there are two big reasons, and they center on the lifestyle and changing life goals and desires. Take a 20 year career template and place it over the course of a "typical" officers life/time span. (I define typical as high school to college to commission to flight school. There are tons of variations, but that's the general flow.)
Ages 18-23: No family. Career is focused on graduation and getting to flight school. Idealistic. Influenced by peer pressure and by other newly minted officers. Little exposure if any to realities of fleet life.
Ages 23-26: Fiancé or Married, no children or 1 baby. Career is focused on surviving flight school and getting to fleet squadron. Idealistic, often says, "I can't wait to get to the fleet." Influenced by peers, and flight instructors who love what they do. Exposure to Navy/Marine Corps is positive. Life has not changed all the much from college yet.
Ages 26-30: Married 2 children. Career is focused on upgrading, qualifications, deployment workups. No longer idealistic. Slapped around a bit. Realize that squadron is full of people just like you trying to stay in the cockpit for next tour. Fights over flight time or lack of it. Squadron politics take root toward end of first tour. Fleet life is cut throat, difficult, with long deployments. Signs of marital stress. Kids start crying when you pull out your overnight bag. First shadow of doubt creeps into your mind, “Is this all there is? Is this what the rest of my life's going to be like? Is there more?” Still trying to figure out how you are going to change the world.
Ages 30-34: Married with 5 kids because you breed like rabbits after deployments and LOVE the Navy, wife is comfy too with your big paycheck stops work and gets a bit of booty/belly, and actually wears the Mu Mu’s you get her on your trips to Hawaii. Waits at home for you with pie and pot roast and a roll in the hay with your flight suit half on……
OR
Divorced with 2 children living in apartment with half your pay going back to wife's hometown in Sandusky, Ohio......
OR
Still married, but with one very annoyed wife who would also like to start a career, build a home and stop all this chasing of the brass ring and the next big assignment. Wife hates your deployment schedule but realizes it's what needs to be done at the moment. Career: Facing first out of cockpit tour, possibly on a boat, or IA to Iraq. Not sure if you'll ever be back to the cockpit. Watch young guys move in behind and eat up all the flight time. You work in an obscure shop in maintenance. You are not the ANI/WTI with all the qualifications so you don’t get the hours that the A$$ clowns in the Ops flying club do. You wish you were them. Idealism has changed to either acceptance of reality ( fat happy wife and realization you will never change the world or that the Navy/Marine Corps is no different than any other job) or you rage inside at all the injustices of the Navy/Marine Corps. You are faced with your 10 year mark decision. Do you stay or do you go?
It boils down to this. The military is NOT a job, it's a lifestyle, the same way being an airline pilot or a corporate executive is not a job it's a lifestyle. After 10 years you either like the lifestyle and have come to grips with all it's oddities and accept your place in life, or you don't. If you don't, then you get out. It's not the money, the benefits, the days of vacation; it's the match of the person to the organization.
As for me, I've opted for a new lifestyle. Will I miss this one? Parts of it, you bet! As you grow up so do your priorities. For me it was when my son asked me to work at Burger King so I wouldn't have to go away anymore in my airplane and we could eat hamburgers together everyday for dinner. You just don't think about that sort of thing when you are 24 in the orgasm and excitement of your first fleet tour blasting into jungle strips in the Bataan islands blowing over cattle and kids on bicycles with your prop wash.