Where do you observe the promotion of the absurd narrative that says that the rich are better humans?
This is kind of like asking where one observes the promotion of the absurd narrative that white people are better people. It's rare to get an explicit source, but you have to benefit from it or be willfully blind to it not to believe it's there.
For one example of a reasonably explicit source, a very loud voice in the US agreed that those who benefits from government services are "the parasite class" (https://www.yahoo.com/news/fact-check-musk-reposted-meme-120...). Leaving, therefore, only the wealthy, who (so the narrative goes) impose no burden on others, to be the virtuous, non-parasitic class.
Them being 'better' in any sense of the word is weirdly orthogonal and juvenile statement.
It doesn't matter if you are a breatthakingly handsome hardworking genius, or you are an ugly imbecile - it's about what assets you own - the whole notion of being better on benchmarks of what humans consider better is irrelevant.
And just because something is present doesn't mean it's an intentional or complete narrative being promoted by the author. This is simply an idea that's virtually omnipresent in Western societies, like the acceptance of capitalism or the system of colors. Things that challenge these sorts of deeply assumed ideas often seem like attacks on society itself. If you want an author who intentionally addresses it, Ursula Guin has made it a big focus of her works (e.g. Omelas, the hainish cycle).
https://oxfordre.com/religion/display/10.1093/acrefore/97801...
The idea of prosperity gospel is strong in the US, it doesn't take much more than looking at US elections and seeing the religious poor voting for Trump and using "because he is rich" as one of the reasons for it.
This also ties into Milton Friedman's "everyone runs on greed" idealisms that permeate capitalism.
I think some of this is because you don't live in the US and get to see behavior like this daily.
Curiosly, in Argentina a popular belief is that "nobody became rich by working" and variations. Being rich here is seen as either the result of luck (born rich) or corruption.