By no means am I trying to convince you to stay, but I do have some questions about your perceptions of post-military employment.
Specifically...
1) I have no idea where I will be my next tour, let alone 20 years from now in the Navy. While if I stayed that long the job would undoubtedly involve me wearing a bird (or else I will be mandatory told I have to retire), there are a number of O-6 positions that are relatively unique in terms of responsibility and scope. I just find it odd that you think a military career is 'safe,' when I've talked to quite a few Sailors who think that most civilian careers would be much more stable - no moving to wherever the Navy sends you, no deployments, no underway shifts, no surges, no sudden weekend emergencies, etc. I tend to agree with them.
2) The military is one of the few careers that mandates promotion. This is a double-edged sword in that you can do well for yourself within the system and get promoted, or you can be told to find another career if you fail to select. Civilian jobs have no such guarantee. If the thought of serving in the Pentagon in 20 years scares you because you'll be doing the "same thing," how do you feel about the possibility of holding the same exact position for 10-15 years, and possibly more?
3) Do you really think that 99% of the people working for any given large company are anything other than indispensible? There are a few key players within these organizations, but by and large the company will continue to exist without you. Or are you looking to make your way with a startup, which could have a much higher payoff but entails much more risk?
I'm not trying to rain on your ambitions, it just seems like your reasons for leaving involves best-case planning: You believe that you are exceptionally talented, that someone is going to pay you for that talent, and that you will have the opportunity to make a large impact on your organization. I'm just curious what you plan to do if that doesn't happen, or if other issues like marriage/children make taking certain career risks, like leaving a company who has passed you over multiple times for the next position, unpalatable to you?
What I get out of Ben's comment is this (and my problem with the system too). It become obvious to most, at some point or another in their career, that they can excel or suck, and for the most part continue. Obviously, most recently we have had a hiccup in the O-3 to O-4 selection process. But I bet you in the coming few boards, maybe even the next one, since we under selected in aviation...the bottom dweller, mouth breather will have a better chance of selection. If you are a middle of the road, does his job but doesn't stretch it too much, you have a reasonable chance of continuing for a career...that is "safe". Now look at it from the hard charger standpoint, no matter how hard he works, he is still promoting with the same percentages, at the same time (ignoring the promotion phasing plan) as the last guy to get selected on that board. That is most likely VERY demoralizing for the #1 guy...and I bet even more so for millennial's.