It still messes me up that Joe Russo said that one of the motivating factors for why Tony took the fight to Titan was because the vision he had of “all his friends dead” is still very real in his mind.
So Tony didn’t just take the fight away from Earth because he wanted to protect Earth. He also did it because he wanted to keep Thanos from the Avengers, because he wanted them to be safe. He is still trying to protect them even now, even after everything that happened.