Under the cut, and comments on this post, are NOT a spoiler-free zone.
So I didn't do a full 18-movie rewatch, but I did revisit the most relevant ones and one thing that really surprised me was how much I sympathized with Tony Stark, not in Civil War, but in Age of Ultron. In fact, I'm still Team Cap all the way in Civil War, but that's in large part because I agreed with Tony in Age of Ultron.
"I should not have been allowed to make this murderbot" sounds like a reasonable stance once the murderbot has trashed Sokovia, but when you take it back a step and look at his rationale while he was working on it, he's pretty damn sane about it. My kneejerk reaction if I had been there (and I'm pretty sure, the first time I watched it), would be "Knock it off, the world doesn't need a suit of armor."
But here we are a few movies later, and yes, actually, that's exactly what the world needed. He didn't know about Thanos, but he knew that more attacks from outside Earth were coming and that he and the Avengers were the only hope we had against them. His nightmare from the beginning of the movie still feels like kind of standard fare genre stuff, so I didn't pay much attention to it, but he spells it out by showing that his fear is that he isn't doing enough. Most superheroes have this in a microcosm: "I could punch this mugger, but what if he shoots me, or shoots the victim, or I punch the wrong guy, or I win too many fights against muggers and become so full of pride that the real threat is me." Choosing to take all those risks is what makes them heroes.
Tony tried to hand the responsibility over to someone else once things went bad, but it's interesting that he wouldn't straight-up retire even while he's broaching the subject of starting a family with Pepper. He's going to be key guy in the reversal of the ending (I'm working on this theory but it's complicated), and I think it has to have something to do with Ultron -- either at a literal level, wherein something he learned becomes applicable, or as part of some revelation that lets him figure out what the world really needs from him.