Ahh but you forget the effects of a Mangekyo, the stronger the dojutsu the more emotional the person becomes, it had the same effect on him as Kurama's hatred had on Naruto and we know emotions affect the ability to rationally think.
In his eyes the shinobi were all defending the actions of a murderer by serving the Kage without question or doubt, and after visiting Konoha he decided he wouldn't kill everyone but become the leader of the world instead, deep down he just wanted to make the world a better place but in a twisted way.
He does have a reason to bring change, he witnessed the murder of his loved ones as a child and grew up without any parents, you should know any normal human being would suffer severe psychological trauma, enough to turn them into an extremist (like victims of war who turn into dictators or terrorists)
Don't see Itachi slaughtering Danzo for what he did to shisui....
Itachi explained to him about MS/EMS and the side of effect of going crazy....Yet he wanna throw all that out of the window.
Idk...If he was really an extremist and didn't use his brain, he wouldn't have lied to the taka team about only attacking Danzo and the elders. He would've just said he gonna do it all by himself and don't give a damn about his team.
He had some "hebi brain" in him while fighting Killer bee. He was thinking about his team and shit. But that kage meeting...He went straight emo for poorly reason if you ask me.
Kishi F-ed period.
Even after the conversation with the 4 kages and seeing Itachi's memory, speaking to the sage of six paths, seeing Madara's way is false, Sasuke still wanted to do something dumb. His family is gone! Kaguya is sealed, the 5 nations are working together. He really had no reason at that point to try and pull a "lelouch" move.
I just don't see any reason for Sasuke to act that way right after kaguya's sealed.
Kishi clearly screwed Sasuke over all for the sake of Naruto's character development.