And yet your deep psychological and technical analysis doen't seem to explain Nakamura's excellent head-to-head results against Caruana
Yes, Caruana lost those games when he was younger (obviously) and still getting stronger (which he is obviously still doing). Caruana won their last game using his superior skills mentioned in the OP.
I found it amusing that a couple of years ago Nakamura complained that Caruana was gaining rating points because he was playing in "weaker tournaments." This shows Nakamura's psychological weakness. He should be working on improving is chess rather than making excuses about why other players are gaining rating points. I think Nakamura should now think about why Caruana is 5-0 in the strongest tournament EVER and Nakamura is in LAST PLACE. Again, I like Nakamura but he obviously needs to fix some holes in his game.
What places Fabiano Caruana above all chess players except Magnus Carlsen? I believe it's how well balanced his chess skills are, his youth, and his psychological strength.
Compare him to Nakamura. Nakamura seems to be unable to "wait" in a chess came. He will play moves that weaken his position just to make the game more dynamic. This is his style. But the chess players at the pinnacle will exploit the slightest "second best" move. Believe it or not, Nakamura is already getting "old." His chance to become world champion (if he ever realistically had one considering his playing style) is probably over.
Nakamura is also not psychologically strong. You can tell that he plays "the opponent" more than he plays "the board." This is a psychological weakness.
Caruana is also getting world-class coaching from Alexander Chernin. Fabiano has always taken his training very seriously (moving to Europe at age twelve).
Nakamura does not seem to be utilizing a coach(s) as much.
I would like to see Nakamura become world champion, but I believe his chances are extremely low now. And if he did become world champion, he would almost certainly lose the title on his first defense like Tal did. Their styles make for exciting chess but that type of play will always be defeated in the long run by a more solid style like Carlsen's and Caruana's.