Only 1 of those people can spend it at any given time. Like a bank account many people can have access. If they all tried to withdraw the balance of that account only the first successful attempt would be valid. So the actual owner of the money was the one who was able to use withdraw it.
Before the bitcoin is used any one of the holders has the potential to be the owner, but it the one that determines it's usage that is in fact the owner.
So it is more like quantum property, which exists in a state of ownership uncertainty until it is in fact spent.
Either that or a far more simple explanation is that the private key is just information and the actual bitcoins, the property are the unspent outputs.
Then where does ownership come in? If the property is the unspent outputs, then everybody with a copy of the blockchain has them.
Ever heard of: Possession is nine-tenths of the law?
What you are saying is the same as saying that because everyone knows where the Mona Lisa is held everyone owns it. And yet that's not true because the picture although it's location being public is held under lock and key in a museum in Paris. It all falls back to how you define a property and how you define ownership.
Here are my definitions:
– property: a scarce tangible entity, corporeal or incorporeal, of which the access to and control of has been restricted and limited
– ownership: the freedom to restrict and limit the use of a scarce tangible, corporeal or incorporeal, entity
These definitions might not be what is generally accepted but they are what I thought of myself as the most sensible ones. And to answer your question, clearly just knowing about the unspent outputs means nothing if you don't have the information needed to turn them into inputs and spend them i.e. if you don't own them.
But doesn't being in a museum imply that everyone owns it? That's kind of the point of a museum, to share and curate a shared culture, which is ultimately owned by no one.
If everyone possesses the unspent outputs, then how many tenths of the law does that add up to? It seems like a lot of tenths. I am frightened by the idea of a rapidly inflating legal system this implies.
If multiple people possess the key information, then both simultaneously have the freedom to use the outputs, but it is not until that freedom is exercised that ownership can be computed and determined by the bitcoin protocol.
I suppose that one thing can have multiple owners, but in some cases one could be completely unaware of the other.
This is further complicated by the m-of-n scenario where multiple keys are used to manipulate one or more specific unspent outputs. How is ownership defined in that case?
The quantum description applies much better than any previous legal term, I think.