No, Eren’s sacrifice was not for nothing. By initiating the Rumbling and then allowing himself to be stopped, he permanently ended the power of the Titans, removing the foundational curse that had driven centuries of persecution and war between Eldians and the rest of the world. This gave his closest friends—Mikasa, Armin, and the others—the chance to live long, ordinary lives free from the immediate threat of being transformed or hunted, while also buying Paradis decades of relative peace and technological advancement that would have been impossible under constant existential pressure. The distant destruction of Paradis does not erase those outcomes; it reinforces the story’s core theme that conflict is cyclical and not solved by any single generation’s choices. Eren understood this. His goal was never eternal peace or the indefinite survival of Paradis as a nation, but to break the specific, inescapable cycle created by the Titans and to secure a future for the people he loved, even if that future remained imperfect and finite. The fact that humanity eventually found new reasons to destroy itself does not mean the lives he protected or the freedom he created were meaningless—only that lasting peace was always beyond the scope of what any one person, even one with godlike power, could guarantee.