~Shippers Welcome~

You know what's really screwed up about Eren's confession to Armin in the end? He admits to Armin that he knew only 20% of the human population would be saved, that 80% would perish, and even knowing that, he still went ahead and enacted the Rumbling. He knew the conflict wouldn't be solved, or ended, by enacting the Rumbling, because he knew the future, and knew that he wouldn't succeed in wiping out the entirety of humanity beyond the walls. He knew by enacting the Rumbling, he would only worsen the conflict and ensure its continued existence. He knew, in the end, that he was in fact dooming Paradis, not saving it. And he did it anyway. He did what he wanted anyway. That's why Armin gets so upset and angry at him, why he asks him so emphatically "why?", because he realizes what Eren is saying, what he's confessing to being. If anyone ever had any doubt, or actually thought Eren did it to save Paradis or the Eldian's or his friends, his confession to Armin at the end unequivocally proves otherwise. Eren did it because he wanted to. Because he wanted to see the sight of an empty, desolate world. That's what ultimately broke Eren, having to be faced with the truth of his own monstrosity. He couldn't hide from it, even as he initially lies to Armin and tries to tell him he did it to save his friends. Eren was a monster. Tragic for how he genuinely cared about his friends, genuinely loved them, but he couldn't put them over his own, selfish desires, and couldn't overcome his own, horrendous nature. Eren is a cautionary tale too, for what happens when we persecute others, and blame others and collectively punish others for things they didn't do. Eventually, it leads to someone gaining power who shouldn't have it. An idiot like Eren, a child like Eren. He never matured as a human being. He never grew. He retained the selfishness of a child to the very end. And we see then what a person like Eren does with that power. Truly terrifying.