Sasuke, from the time he was a child, was never good enough. He wasn't good enough to be acknowledged by his father, he wasn't good enough to be taught by his brother. He looks up to Itachi, he idoloizes Itachi, he tries to be Itachi, but he can't ever reach Itachi's level, and he knows it. So does Itachi. He spends the first eight years of his life being measured against the impossible standard of his brother. The one time his father acknowledges him has much more to do with Itachi no longer being suitable than it does with Sasuke finally measuring up. Sasuke is the last resort, the booby prize, the reserve item. What does he have to be arrogant about here? Spoiler: Then Itachi slaughters every single person in the entire clan except for Sasuke? Why? He says, to Sasuke's face, that it is because he does not consider Sasuke even worth killing. Sasuke ends up begging for his life like the frightened child he is, and it is clear that he believes Itachi's claim that he is too worthless to kill. There's not even a hint that he considers that Itachi could be lying about that. So Sasuke spends the rest of his life training hard enough to become someone strong enough for Itachi to acknowledge. Because he feels utterly worthless. Enter Naruto. Does Sasuke imagine himself to be a better shinobi than Naruto? At first, sure. Sasuke can dismiss Naruto because he has nothing to do with his desire to be acknowledged by Itachi. Does Sasuke imagine himself to be more important as a person than Naruto? I would argue "no" because Sasuke sacrifices himself for Naruto during the Zabuza arc in a way much different from the "showing off" he did when he saved Naruto earlier in the arc. Sasuke's body "moves on its own" to take the (seemingly) deadly hit for Naruto: why? Firstly because Sasuke does realize he is part of a team and Kakashi's first lesson, that letting your team mates die is an action only fit for those lower than scum, resonates deeply in him. But also because Sasuke doesn't think his life is worth as much as Naruto's. What is there to be arrogant about there? Skip ahead to the Akatsuki arc, in which Itachi and Sasuke meet again. Not only does Sasuke have the unfortunate realization that for all his training, Kakashi's special chidori technique, the hard work he did, he's still not strong enough to be acknowledged by Itachi, there is the added blow of Naruto, his rival, being the one Itachi acknowledges. V of the E, Sasuke takes the power Orochimaru offers him in exchange for the chance to defeat Itachi. Some people suggest this is because Sasuke believes that Orochimaru will never get the chance to take over his body, that he could stop that before it ever happens. And that would be arrogance. Spoiler: But, recent canon suggests that this isn't true. More likely, Sasuke just doesn't care about what happens to his body. He still believes he is worthless. The possibility of killing Itachi, getting his revenge, finally being acknowledged by his brother overrides any concern he feels for himself. When Sasuke says "I am more special" to Naruto, I take that more as a desperate declaration to himself then any large boast. Orochimaru wants him. Orochimaru acknowledges him. Orochimaru marked him, and even if the mark will eventually distort and destroy him, it's something Sasuke is willing to accept in order to reach Itachi. About the only thing Sasuke doesn't want to do in order to reach Itachi, is become Itachi himself. It's that desire which stops him from killing Naruto. So, while I am completely amiable to the idea that Sasuke believes himself to be stronger than some people (which might be arrogance in the case of Naruto, Sakura, and Kakashi) I am not so convinced of the idea that Sasuke believes himself to be better than others. Sasuke has very low self-esteem, in my opinion, and this is what makes him so easily manipulated by those around him, namely Itachi and Orochimaru.