At age 13, he met his idol.
All might has always been the light shining into the darkness for Izuku. He thought meeting the man would be forever engraved in his memory as a momentous occasion... And it was. But not for the right reasons. Because Izuku asked his question. And the answer brought him to his knees.
At age 13. He gave up.
He stopped everything. No martial arts, no gymnastics, no schoolwork. No analysis. He was tired and broken by this system of bigotry and discrimination. So he quit... Put down his notebooks, shut his mouth, and slept with his eyes open.
He'd seen the dark side of the world and turned his back.
Until it came.