Twenty years in the military is a long time. It’s like dog years or something.
One military year seems like at least two civilian years.
And not everyone is 38 after 20 years…but it certainly is possible to retire at that age. As an officer, it’s either “up or out,” meaning that either you get promoted, or you are out of the service. The higher in rank you get, the fewer positions there are to be promoted into.
**Midjourney attempt at a self-portrait of the author about 20 years ago. One year before retirement.
Getting your 20 years in is actually a pretty good deal. You draw half the base pay of your highest rank plus a bunch of other benefits.
I know more than one person who retired from the military around age 38, got another federal job and then retired from that around 58.
I can think of any other jobs where you can do that.