I don't know how wealthy he'll be.
Assuming his ticket was like most tickets, it said that he could be bumped. There are even express laws regulating when passengers can be bumped involuntarily, the required compensation, etc. United didn't just make this up on their own. And airlines are within their legal rights to have passengers who refuse to be removed, removed involuntarily by police or contractors. Normally, companies are willing to settle claims that hurt their image, but there is a real issue with precedent here. If this guy gets tossed a pot of money, then you're going to see a lot of other passengers refuse to comply when ordered to deplane. It may have the perverse effect of encouraging more confrontations. So, speaking as a lawyer, this is one of those situations where you would encourage your client to fight it out -- at least for awhile.
I'd point out that those crew members were very likely heading to be the crew on a different plane. If they did not make that flight, then an entire other flight would have to be cancelled, and all those people delayed.
Bottom line is that you simply do not have a legal right to refuse to deplane when ordered to do so. This guy apparently believed that the rules that applied to everyone else don't apply to him, so he refused. He found out that he's no better than anyone else. Honestly, I have absolutely zero sympathy for this guy. You were told to leave, so leave. Is that really so hard?