I think it's the meaning of the upper class which has been eroded by the super rich. If you have rich parents, went to an ivy league university at their expense, and own a collection of art or human remains, chances are you're upper class in my book.

I believe doctors should be considered upper class in a well functioning society. It shouldn't be reserved only for undeserving billionaires - at that point both the middle and the upper class become deprived of meaning. I rather think the ultra rich should be treated as a separate category entirely (and one all three of the other classes should unite against).