It's probably just as well that Doctor Doom is a super villain, I don't think he'd be very good as an MD. You can just imagine all his patients telling the receptionist that if it's all the same they'd rather see another doctor in the climic as having their illness treated by someone called Doom doesn't leave them feeling very optimistic about his prognosis. Plus the mask and the hood are a little offputting.
Similarly it must be hard to get a date with a name like Doctor Octopus, and job interviews are probably a waste of time when you are called Doctor Psycho, unless you are applying to join a death metal band. Hero names are so much more positive - who could help but feel good around Mister Terrific? And you just know that when Sue Richards is talking with her girl friends about her husband, at some point she has said, with a sly wink "...And they don't call him Mister Fantastic for nothing."
Doctor Doom is never going to get that kind of action. No wonder he's so grumpy.