My understanding is that European royalty generally thought of their positions as being granted by divine providence. I guess it's slightly different because they didn't attain their position (they were born into it) but I think there's little question they generally considered themselves inherently morally superior to the poor.
Really, it seems like the mechanism may have changed; "I am successful because God has chosen me in my inherent superiority to be successful" vs "I am successful because of the inherent superiority of the moral code I follow", but they're really just different applications of the just-world fallacy. Which, in turn, is a natural product of the way our brains are wired.
note that the article isn't really talking about aristocrats, whatever their modern equivalent would be, but today's upper middle class. The kind of people who work for a living, highly paid for sure, but who aren't rentiers or factory owners.
As far as successful burghers or artisans in the middle ages, then yes, I think they did ascribe their financial success as resulting from God's blessing their superior morality.
Really, it seems like the mechanism may have changed; "I am successful because God has chosen me in my inherent superiority to be successful" vs "I am successful because of the inherent superiority of the moral code I follow", but they're really just different applications of the just-world fallacy. Which, in turn, is a natural product of the way our brains are wired.