I Haven't Seen Anyone Address This Before But I LOVE It - Tumblr Posts
I do have an explanation for this actually!! I first saw it being mentioned in one review of TSH I saw on YT, which I will link as soon as I'm able to find it again.
The Secret History was written by Procopius of Cesarea, a Greek historian who lived from 500 AD to 565 AD, so at the time of Justinian's empire. He got to accompany Justinian's general during his war campaigns, and so he was commissioned most likely by Justinian himself to write about the wars (History of the Wars) and his deeds in favor of the Empire and its subjects (Buildings).
The thing, though, is that since Procopius had written his works on Justinian's behalf, it's believed that many of his accounts in regards to Justinian and his court were not exactly true. Especially since historians actually found some discrepancies between Procopius' words and those of other historians, as in him attributing Justinian merits for things he hadn't actually done and so on. He also presents the Emperor and the people surrounding him in a way that's very idealized to the point of sounding exaggerated.
But then Procopius wrote another work, The Secret History, which actually he had published after his death, in fear that he could have angered Justinian and possibly be sentenced to death had it come out during his life. In The Secret History, Procopius talks about Justinian in a totally opposite way of how he did in his previous works – as opposed to idolizing him, he paints him as cruel and even incompetent in ruling. He claims to expose all the secrets, personal lives, scandals, rumors, everything bad he knows about Justinian, his wife and even his general, to show how they actually were and his actual thoughts about them, which he was forced to hide in his other works.
(It's also debated if The Secret History itself has to be considered accurate, because it's believed that it could have been just a safety measure for Procopius to use to distance himself from the court had Justinian's government been overthrown, to show he wasn't actually loyal to him and not get in trouble with the new ruler, so we don't know for sure, but anyways.)
How all of this connects to TSH by Donna Tartt is that the way Richard talks about the Greek class is pretty much exactly the same as Procopius. For most of the book Richard treats them as superior, tries to hide their faults and justify their actions, and tries showing them as he saw them at first – good people he admired. Only for the illusion to slowly break during Book II, in which inevitably things start being shown as they actually were, and Richard becomes as disillusioned with them as Procopius did with Justinian.
Of course this is just what I found so if anyone knows better feel free to correct me or add things!!

Yesterday I found this book, its set in the late Roman Empire and there is no way it isn’t related to The Secret History.

