Board Thread:Naruto Discussions/@comment-3291244-20140611195547/@comment-3291244-20140613015843

Darhumphump wrote: the most frequent and obvious motif of the show is no matter who you are you're better off if you have friends, comrades, or allies on your side. Sasuke tried to get as powerful as he could by going off with Orochimaru and trying to be his own person and only got more powerful when he joined his old team. You're all right if this were real life, but in this universe you won't get anywhere if you don't use teamwork.

Sasuke fully acknowledges that he cannot defeat Kaguya alone, and he needs Naruto's help in order to "save humanity" as he put it, since he fully acknowledges Naruto's power. That's why he saved Naruto with his Susanoo, and once again with his summoned hawk. However, this is so that the mission to save humanity can be accomplished. Sakura and Kakashi are far outclassed by Kaguya. They are not important to the mission, hence why Sasuke feels like they would be a continued burden to the mission if he had to keep saving them over and over again. This is why he doesn't feel the need to save them.