As Rich As Korach, Or As Rich As Croesus?

Head of Croesus on a Vase in the Louvre, Paris

"As rich as Korach" is a fairly common Hebrew phrase, used by religious and non religious alike. The origin of the phrase was recently the subject of a small written piece in Shabbat Be'shabato. Korach (Korah) is not attributed any great wealth in the bible. Where did the midrashim learn that he was wealthy?

Two weeks ago "Shabba Be'shabato" published this short piece trying to establish why the midrash associates Korach with wealth:

 " What is the source for the Midrash that describes Korach as a very wealthy man? What is the basis for the expression, "As rich as Korach"?
One basis for this approach is logic and experience. From the dawn of history and until today, wealthy people try to rule their surroundings. The text of this week's Torah portion has mild hints of this situation. For example, the Torah takes the trouble to note that Korach's possessions were swallowed into the earth together with him. But this is not really enough to serve as a basis for the Midrash.The offspring of Korach dedicated an entire psalm to the subject of wealth: "They who trust their riches, and are proud of their wealth" [Tehillim 49:7]. The descendents of Korach speak of the lack of any value of wealth after the death of a rich man. In the same psalm, the children of Korach also use the terms "hell" and "descent" – perhaps this is a hint about their wealthy ancestor, Korach, who was sent down into hell. This is the meaning of the verse, "There is no authority on the day of death" [Kohellet 8:8]. This describes the total separation between wealth and government authority.The descendents of Korach end their psalm with a ray of hope. "Do not be afraid that a man will gather wealth and increase the honor of his home, for he will not be able to take anything when he dies – his honor will not descend after him" [Tehillim 49:17-18].

I didn't find the explanation that convincing, but I didn't think of this again, until I read this short letter published this week:

Bar-on Dasberg tried in vain to find the source of the expression, "Rich as Korach" in Tehillim. The original source of the expression that appears in the Midrash is not related to Korach in the Torah but rather to Croesus, King of Lydia, who lived in the sixth century before the Common Era, and who was very rich. After his death he became part of Greek mythology. See the article about Croesus in Wikipedia. In Hebrew, his name took on the form Korach, and this is the source of the error.     (Rabbi Israel Man, Toronto) 

Is it possible that the expression "Rich as Croesus" could really be the origin of the term, rich as Korach? One can understand Rabbi Man's explanation in two different ways. The first would be to claim that the very tradition that Korach was a rich person was due to the correlation with greek history. The second would be more minimalist and claim that the phrase "Rich as Korach"  came about because there was a similar Greek phrase. I tend towards the second understanding, but can't really see a reason why the first understanding isn't possible, given the antiquity of the Croesus account in Herodotus

My limited online search has not yielded any great contribution. Google books shows that quite a few books do translate Croesus as Korach – but unfortunately I can't see the full text of those books and as such can not look at their sources. However, were we to reject Rabbi Man's explanation we would be faced with having to explain a very odd coincidence.