Your reasoning holds for those of us with ordinary egos. But Christie is a politician; his ego is enormous and a tremendous amount of his self-worth is based in the adoration of strangers. He wanted the job and has a high enough opinion of himself to think he would get it. You're correct that he never had a chance. But you're mistaken about the other part: He was the last person in the world who believed he wouldn't get the offer.
As I posted elsewhere, and at greater length, Christie did what he did with full deliberation. Whether the reason for that was resentment (my theory) or his own reelection bid is immaterial. He did it willfully and with full understanding of what he was doing. Like an actor, he is a politician of some ability and that means that he manipulates public perception for a living. To believe that he spontaneously embraced the flailing leader of the political opposition in a moment of genuine emotion in the full glare of the national spotlight in the last 100 hours of the news cycle is like believing that Lawrence Olivier would spontaneously jump in front of a camera and lapse into Hamlet.
In any event, it doesn't matter. He has no future in the Party outside of Jersey, and unless he has an eye on a Senate seat that he'll need money for (and doesn't think the other Party will provide), I expect him to pull a Specter or have a Bloomberg moment very, very soon.
1. He's a fat slob with a New Jersey attitude (I'm fine with both of these, by the way), and his "shtick" would not have played well in any swing states.
2. He didn't stand a good chance of bringing his own state into the Republican column in 2012.
3. His career in elected politics has been less than three years in the governor's office in one of the most reliably dysfunctional states in the U.S.
4. His prior career as a Federal prosecutor might have played well in a campaign year where "law and order" were major campaign themes, but not in a year like this where the economy is front-and-center on the national scene.
5. New Jersey's unemployment rate is nearly 10% -- which is more than two points above the national average. Christie still has plenty of work to do in New Jersey.
Personally, I don't think Christie's plans have changed at all. He's going to run for re-election in 2013, and if he loses (or even if he wins), he's going to be angling to serve as the U.S. Attorney General in a second Romney term. He may even be a potential candidate for this post in January 2013.
So there you have it. If you have any evidence that Christie was ever seriously considered as a VP candidate by Romney (or even wanted the job), have at it. Your post is filled with a lot of speculation about an ego that is so irrational that it wouldn't even consider his own huge shortcomings.
As Mitt Romney has once again demonstrated to us, candidates from states east of the Delaware River simply don't do well in national races in this country. I may be wrong about this, but I believe JFK -- in 1960 (more than 50 years ago) was the last person to win at the national level as president or VP on a ticket.