OP -- I read your posts to my husband as there was something about them that niggled my memory about college. He reminded me that there used to be a man in his college circle of friends/acquaintances who behaved in this manner. One day, someone got annoyed enough to call the man on the behavior. I do remember that moment clearly now that my husband reminded me because we had all sort of thought he might be in our university's deviant psych class, which had a requirement that every student act "deviant" in public in some way and record the responses. Therefore, we all thought the explanation for his behavior would be reasonable (even if the length of the "deviancy" had gone on far longer than normal) and more importantly, that he would knock it off since he'd been "outed."
Instead, the man's response was that he behaved like that because (I'm paraphrasing, but the meaning is the same): He liked to confuse and irritate people for the "fun of it". He enjoyed seeing people get confused and try to be polite about the situation and try to be polite to him. He thought it was hysterically funny to watch "polite people squirm when I am being so rude." He went on to say how he'd go home and relive the "fun" in his head. He said this all with such... glee and delight, clearly thinking himself far superior to the rest of us. We all thought he was at best a jerk and at worst, some sort of sociopath. He was cut out of the group immediately.
(Edited because my original sentence structure was awful!)