a lot of people in the naruto fandom says itachi was the only uchiha who wasn’t cursed or didn’t succumb to the uchiha curse but personally i think that loving too much is part of it. he did love too much his little brother; so, so much that he did what he did, all to protect him.
besides, what do ya’ll think he would do if sasuke was hurt by konoha while he was still alive? dude was a pacifist traumatized by a war itself but he was willing to start another war if someone touched one single strand of sasuke’s hair by revealing konoha’s secrets to the enemy nations, as said on itachi shinden.
i mean, he did not succumb to the hatred curse indeed. because he succumbbed to the love curse.