This is my favorite, when it comes to discussion of "big ticket treasures" (and the oft-times unconventional methods that seem to go hand-in-hand with finding them) : When you press the believers/advocates for examples (proofs), then .... it's like here: The suggestion (albeit veiled) that big-ticket treasures are being found. But ... lo & behold : They don't show or tell anyone. Because they're afraid that the I.R.S. might come to claim taxes.
Another variation on this is: They're afraid that thieves might target their house. Right ?
But oddly: There is always accounts, made public , of treasures found. Even here on T'net, some mighty nice stuff (even caches) makes it's way on to our show & tell "Today's find" section (yes, even caches sometimes). Did any of them ever have the IRS come knocking on their door ? Were any of them the target of thieves ? And bigger ones found, for example, in the news, by const. workers. Or by someone walking their dog. Or by some dude named Mel Fisher, etc.... Doesn't seem to have stopped them from claiming their well-deserved bragging rights.