Wouldn't the scarcity of the items increase the value? It seems to me that knowledge of the find reveals them to be less scarce, and limits the value somewhat. Selling them as rare items a few at a time should result in a higher total, shouldn't it?
Probably so, but to think you would put $10 million dollars of these coins on to the market without verification does not seem realistic. And to get that much verified would be very difficult to keep secret while generating enough interest to get the best bids.
If I found these, going through a gold coin “broker” while keeping my name out of it, and public to generate the interest seems like the way to go.
I’m not going to be capable of adding $10 million in wealth and think I’m going to hide it from the government/taxes.
If I was a buyer, and understood the seller needed to keep my purchase secret so as not draw attention for the other coins and associated taxes, I’m an not paying top dollar. And personally, I would walk away because I don’t trust at that point I’m buying a real coin.