[[ I would not say insane, that’s a loaded term, and Itachi is in control of his faculties. He still understands the concepts of right and wrong, he still feels guilt for his actions, he can follow orders and control himself.
Itachi at the very least hast Post Traumatic Stress Disorder from what he saw in the war, and the massacre itself. He also has a lack of self preservation and suicidal ideation, given he wants Sasuke to kill him and views his own life is worthless. He’s only willing to live as long as it takes for Sasuke to kill him. ]]
