"Personality disorders" have adverse affects on others, not just the person with the disorder. As for Trump, you really think he's happy? Purportedly he's angry almost all the time. Did you see his behavior on 60 minutes? Is that the behavior of a happy well adjusted person?
Deep down Trump knows he's shit which is why he requires constant adoration from others. If he loses this election, he will go into an emotional tailspin because his ego can't face the idea of losing. The problem is that you're defining one's well being by external measures of success, like power and wealth. But you're missing the fact that you can have those things and still be utterly miserable.
I guess it only becomes a 'disorder' if it makes the sufferer sufficiently unhappy that they voluntarily seek psychiatric help. And that is going to depend on what else is going on in your life and how those around you react to your dysfunction. Trump is probably unhappy but not as unhappy as he would be were he also poor and powerless, with the same personality. Generally those at the lower end of society are far more likely to end up meeting that criteria for diagnosis, because they are far more likely to end up suffering the consequences of their dysfunction.
The point about if he loses the election implies that it only really manifests as a disorder when it leads you to recieve some sort of comeuppance. But if you succesfully evade such a comeuppance then that would imply it wasn't a disorder after all ("The important thing is, I didn't get my comeuppance. No Comeuppance!" - Homer Simpson, and also potentially, Donald Trump).