Would you expect a doctor to rescind his hard-earned title upon retirement? I think not.
”Doctor” is generally a qualification. As in PhD. Corporal, Lieutenant, Admiral etc is an appointment. Once you retire you no longer hold that appointment.
People who cling to such things, having lived most of their lives through their ‘rank’ just look sad.
Though I accept my view may be influenced by my time in the Royal Air Force where many NCO techies could be better qualified than a fair few officers.