Tony went silent at that truth because he just -- well. For whatever reason, he hadn't thought of it. Hadn't thought of his own future sacrifice actually making those sorts of choices. It was easy to think things like "I died to fix it all' and much harder yet to zero in on all those details, exactly how much would be fixed.
It had already been worth it, or else he wouldn't have done it -- some future version of Tony had done the math and decided the cost more than worth the results -- but knowing those smaller details? It really cemented it all in his mind. Even knowing what it was he would lose.
He fell silent for a moment though, biting at his bottom lip for a moment while Steve shifted, laying on his back. Tony scooted forward until his stomach was pressed up against Steve's side. "No one owes me."