I loved that you mention Yinsen, I feel he was a major contributor of shaping Tony into Iron Man. Of all the things that Tony experienced in that cave, you never once hear him mention Yinsen to anyone. Ever. He holds that close to himself (We know Tony's guilt on such matters) He talks about the soldiers that died for him, but he always skirts around the subject of what exactly happened in the cave.

We truly see Iron Man for the first time when he goes and liberates Gulmera (Yinsen's home) Tony reacts almost emotionally to the news broadcast, he is sitting there doing nothing while people are being oppressed, murdered with HIS weapons. (that he recently discovered were sold under the table. He had been blissfully ignorant for years) He already let too many people die for him. We see the determination when Tony puts on the armor to take action.

And also Yinsen's final words to Tony. "Don't waste it." When Tony thanks him for saving his life. Think of the weight that Tony carries now with that hanging over him. Did he let this man die for him in vain? Tony is famously self destructive, and you know he uses that as a partial motivation to keep going.