There is no auditing whether he sold all his keys in the physical world. They may never have "transacted" on the blockchain, but that does not mean he never just gave away the ability to transact them physically.
He may also have taken out a loan from a traditional financial institution and used them as collateral.
There is a very real possibility that they are in fact owned by someone else now, who has made the same exact calculation you have - they are a valuable asset that has exactly zero liquidity.
> There is no auditing whether he sold all his keys in the physical world.
Are you trying to claim that someone would buy Satoshi's coins without moving them to a wallet they control?
In this scenario, the person would have 'purchased' the coins with precisely zero assurance that Satoshi wouldn't just move them to a new address at any point, as he/she/they still have the private keys.
As I said, it is impossible to verify that that isn't the case. He could have taken a loan with the whole wallet as collateral. That isn't the same as claiming that Satoshi did that, but it's not like the audibility of the blockchain spreads all the way to the real world. There's really no saying what Satoshi has done, and the anonymity means there's no way to find out.
It.. doesn't work like that. Suppose someone sells you a private key, or even a hardware wallet, claiming that it "contains much Bitcoin". There's no way for you to be sure that the seller doesn't have a backup. Or is selling ten other copies to other people.
It's like trying to sell an account by selling the password to it. The first thing you do is change it so the previous owner can not get in anymore. Before you did that you can not be sure that you are the only one with access. On Bitcoin the only way to change the password is to move the funds to a new address.
The only way anyone could assume control of the account as collateral is by knowing the private key. If the funds are not transferred to another wallet, then both parties now have knowledge of the private key. As such, the entity providing the loan has to trust that Satoshi will not move the funds. That would be an insane risk to take.
But would someone ever buy bitcoins from someone without actually permitting a transfer? How would you ever have an assurance that seller has relinquished control of the coins?
Example: I own one coin. I sell my private key to you for $5k fiat. You take my private key and sit on it thinking it’s yours. After a use a copy of the private key to transfer the coin to a new wallet I own. I’ve now stollen the coin I supposedly “sold” to you.
He may also have taken out a loan from a traditional financial institution and used them as collateral.
There is a very real possibility that they are in fact owned by someone else now, who has made the same exact calculation you have - they are a valuable asset that has exactly zero liquidity.