GDER, that's a darn fine question, and a really scary one too.
At my last duty station (a training command), most of the enlisted retirees thought that their pensions wouldn't be enough. No one demonstrated the financial-management or frugal-living skills to fantasize about escaping from the workplace. The retirees would have the ceremony on Friday and come back on Monday as a contract employee or a civil servant, often collecting a new paycheck while still on terminal leave. Sometimes it'd even be the same department and largely the same job (within govt ethics guidelines, of course). I've been to a couple ship reunions and it's the same story-- everyone working, some shipmates in very successful careers, but no one retired. Sadly, a number of them knew that they'd be surrendering half their pension to their divorced spouses.
As near as I can tell, the vast majority of my (living!) college classmates are still chugging away. I don't know if that's because they're future flag officers & CEOs or if it's because they don't know how to ER. And a significant minority hasn't reported in at all, so as you say maybe ERs don't contribute to alumni magazines & websites. I can name half-a-dozen military associations designed to network & build careers, but I can't even think of ANY groups for ERs (other than boards like this one).
I can only recall two people-- a meteorologist (commissioned from the ranks and retired at 20), and her friend (a Marine Corps warrant officer). She's a professional sculptor and they live off their pensions. Everyone I see on the waves on a weekday morning is sneaking away from their offices.
I don't know when you escaped the asylum, but as recently as two years ago you had to attend your local "Transition Assistance Program" before you could retire. It began as a week-long course during the DESERT STORM drawdown-- including a full day on how to dress for success despite 20 years of coveralls & cammies-- but it had shrunk to two days by the time they snared us. Spouse & I were relentlessly brainwashed on how to qualify for VA hiring preference, how to ferret out civil-service jobs, and how to work with a headhunter.
But the entire course was designed to help us FIND a job, not get rid of one. There were a couple references to post-career depression & losing your "identity", but the only solution was to create a NEW career identity (in your subdued yet fashionable gray suit, no less). My spouse and I were fortunate enough to attend the course together and we realized very quickly that we weren't fitting in. We spent both days hiding in the back row with our eyes on our "work"books.
The course did one good thing for me. I was discussing the whole experience with my father (retired for 10 years at that point), who knew about our military pension and our retirement portfolio. I was frustrated that the career skills inventory & interest surveys kept pointing me toward nuclear engineering jobs. He's a nuke too and he understood. He asked "If you can afford not to, why in the world would you want to get a job?" That stopped me in my tracks, and I started paying more attention to his lifestyle. I haven't looked back but I sure enjoy running into old shipmates.
The interesting thing about leaving military service is that, deep down, you have no clue what a civilian employer seeks. You learn it all from books or by talking with family & other "retirees". Meanwhile the employers are dying to have mature cool-headed managers & technicians with solid work ethics & experience, and they can't believe how you underestimate your value. I never attended a job conference or even wrote a resume', but on the first day after my sixth month (those govt ethics guidelines again) we had three unsolicited queries in one week. (Unfortunately none of them included time off-- with pay-- for high surf.) But if those offers don't inflate your ER ego then I doubt anything else can.
Now I think I'm going to ask some pointed questions of my alumni association & other organizations...
