I have never been in the military so have no idea why those who have see it necessary to use a title they no longer hold or need. The master of the foxhounds I had to deal with in my water main laying days in Cheshire was one who insisted on being Captain Something .... and talking with a ridiculous plummy accent that just got up everybody's nose. I was also led to understands that ex military men are permitted to call themselves by a rank one higher than they actually served with. And those with a problem with the pompous "Captain" would mutter that he only ever held the substantive rank of Lieutenant.
However, to my real question, I spend some time in the USA and it amazes me how may people have car number plate surrounds or wear caps that say "I fought in Vietnam" or "Ex Marine Corps" etc. (usually followed by "and proud of it"; which I am happy they are entitled to be.)
Surely that sort of blatant advertising is just asking to be a potential target of the ungodly ?