2. Arrogance
A real super-villain isn't complete without a touch of arrogance and Doctor Doom has it by the bucket-load. Doom has a massive sense of self-importance, a real superiority complex and vanity, conceitedness and pride that is bordering on ridiculous. He is, of course, royalty in his native country of Latveria and has a hell of a lot going for him that gives him every right to be a bit arrogant - affluence, intelligence, resources etc. - but he knows this all too well and lets everyone around him know on a regular basis. As far as Doom is concerned, no one - even his arch-rival Reed Richards - has a more brilliant mind than him (although Doom has massive insecurities about this and, deep down, knows that Richards is on his intellectual level at the very least) and no one can match him in pretty much any category. But it is this complex that keeps Doom at the top of his game and contributes enormously to what makes him so much of a threat.