Just heard McCain on MS-NBC’s documentary talk about how at Annapolis, his intention was to see what he could get away with, while still remaining in the school.
Seems to be a lifelong theme.
I don't think that's too uncommon when something like that (an Annapolis education) is just given to a person. Remember, with his admiral father and grandfather, McCain's getting into Annapolis was never a question. And that would give him a different outlook from someone else who had to work their ass off and earn an appointment to the Naval Academy.