Perhaps that's why the Master is driven by the drumbeat. Voices telling him to kill and destroy drove him to the edge, then as a desperate attempt to stop the madness, he found the drums. But he didn't realize that the drums were what would make him insane. The constant, incessant sound of drums pushed him closer to the precipice of his mental stability, but the bloodshed of the Time War drove him into the freefall of insanity. He tried to fix himself, but the antidote became the poison.