i did follow your reasoning and although i agree to most of the key points that you are making, i think you forgot to account for people like me who do not really buy credits often but are active enough to save up (i usually only buy the 295 cred packs) that when the new packs
came out (which are undoubtedly a better deal even compared to the 295 cred ones) i was able to buy quite a few.
Now i have several duplicates but i just happen to be the type who do not mind doubles and don't feel like selling them since i have enough clintz as well. However, that might not be the case for other players who have saved up credits but do not have clintz.
If one were in such a position, one can understand how having duplicates might mean that it would be better for them to sell the medium or high priced ones for solvency.
again, all of this is just our speculation and i will always agree that correlation does not necessarily mean causation, but if there were enough people experiencing the aforementioned scenario (or some similar version of it), it would be logical to see a sizable influx of cards to the market which will decrease prices.
Now i also understand that having hundred copies of a card and flooding the market does not have to mean a decrease in price (one can sell them all at the same price), however, if it were hundreds of different people having one duplicate each and trying to undercut each other, it would be logical to see a decrease in price.