I think a lot of the HN crowd identify less with Tony Stark as an ass-kicker, but more because he's one of the few superheroes that you can truly say is a "self-made man" (pun unintended, but apt). He's amazing not because of some genetic accident, but because of his own intelligence.

I don't remember the character being as much of a jerk as RDJ plays him, but admittedly I only ever watched the cartoons as a kid, not read the comic books.