Going full circle
The rehabilitation of Tony Stark from irresponsible playboy arms dealer to sacrificial hero of the world is, in the opinion of many, the overarching plot of the Avengers’ storyline. When we first meet Stark he doesn’t really care about anyone or anything, but by the end of the first Iron Man film, we see him look death in the eyes as Obadiah Stane attempts to kill him.
This scene looks remarkably similar to the moments between Thanos and Iron Man in Avengers: Endgame as we realize that Tony is going to give his life for the sake of his team, and the world. The mirroring is an elegant way to close the story arc of this irreplaceable character.