If you lock something in a safe and you own the key (so only you can move it) do you now only own the key or also the item's movements? I understand your point from a ledger point of view, bitcoin never leaves the ledger, but "owning" something digital bitcoin comes very close to that once you "own" (are in posession of) the key. If you know the secret key, do you "own" the key? If you hold a bar of gold, don't you "own" it solely by the ability to control its whereabouts?