>It's popular to say things like some government employees are "folks who can't hack it in civilian life," but there's basically no evidence this is true.
I'm not aware of any scientific studies, but I spent a decade on active duty, and seven years as a reservist so far. When it came to technical jobs, almost everyone was terrible at their job, which was usually an incredibly narrow and overly simplified version of what the job would actually be in the civilian world. Everything is compartmentalized to the point where even if you excel at your individual responsibilities, you would still be terrible in the broader field. Almost every marketable skill I learned during my time in the military was something I did on my own time that was completely unrelated to my day job.
After I left the military and transferred into a different kind of technical role, eventually I started helping with interviews. 15-20-year government service veterans with incredible resumes and sr. titles are regularly found to be unfit for even an entry level job.
There are exceptions, but the rule in the military is incompetence. Its not that there's something inherently wrong with people, its just that the military recruits intelligent people, trains them very poorly, and then never lets them do anything remotely interesting or challenging. They just follow whatever steps they were told to complete in training over and over again for the rest of their careers.
As with anything, there are exceptions. Some tiny parts of the military do interesting work and have developed a culture that's reasonably conducive to innovation and fostering talent. From what I've heard, parts of the NSA used to be like this, but the lack of ethics among the organization's senior leadership ended up being partially responsible for the reorganization. Additionally, there are other people that manage to become really good at something in spite of being constantly strangled by the government's attempts to hold them back. Some of the most brilliant people I've ever met started out in the military, but the overwhelming majority of people that serve in technical roles are unfit to do anything besides put asses in seats for the defense contracting industry (which 95% of the time isn't any more capable of specialized technical work than the military).