system
Given the following post, respond as if you're commenting on Reddit:
human
[Avengers AoU] Why did Tony blow up all his suits at the end of IM3, only to build another one?

I thought this would be touched on in the movie, but it wasn't mentioned. He sounded like he was retiring for good at the end of IM3, but by AoU, he is even more invested in the superhero business than ever. So what caused the change of heart?
gpt
His revelation at the end of Iron Man 3 was that, as he puts it "*I* am Iron Man," with emphasis on the 'I.' He built those suits to cope with his stress and trauma from the Battle of New York. By destroying them, he was going clean slate and allowing himself to start over. He never intended to stop being a hero, and his suits are the best way for him to do that. He just wasn't going to let his suits define him.