Don't let yourself get seduced by the narrow dogmatic view of the jedi council. In order to be a great leader one most understand all sides of the puzzle.
Fear leads to anger, anger leads to hate, hate leads to POWER UNLIMITED POWER
Except Bane knew that he had no political aspirations, he knew that he was merely the first step in the Sith's revenge against the Jedi, he knew that his job was to begin the long gathering of knowledge and the creation of the levers that would eventually create the downfall of the republic and the Jedi Order.
He knew his place within the darkside and that made him different from all of the other Sith Lords who eventually tried to seize power in the mundane world.