The three million figure is speculation and uses the flawed logic that satashi will never spend his coins (if this were true, I would think he would have destroyed them by now).

Also the vast majority of the bitcoin that are "lost" are really not truly "lost" but rather claim to be "lost" as we do not have any real way to know for sure that the private keys really are inaccessible  but rather have to trust the person who claims to be the previous owner of the keys that they really lost them