I disagree. It's because of Itachi. He's too arrogant to think he couldn't beat Naruto if he really tried. However, he still feels he couldn't beat Itachi no matter what. Honestly, without Itachi Sasuke would be just a half brain idiot tool for Tobi to exploit. You might be right that he's only seeking more power, but if he is, it's not because of Naruto.