Bitcoin ownership is established through digital keys, digital signatures, and Bitcoin addresses.
A Bitcoin address is the deterministic output of a cryptographic hash function that takes a private key as its input. Digital keys and Bitcoin addresses can be produced without being connected to the Bitcoin protocol or even the Internet! In fact, “accounts” are actually just abstractions we use to describe digital key pairs. It’s literally just two numbers that are related to one another. So technically, every account has always existed everywhere, and you can use any “wallet” to access any account as long as you know its private key.
“In bitcoin, there are no coins, no senders, no recipients, no balances, no accounts, and no addresses … Thus, a user’s bitcoin “balance” is the sum of all UTXO that user’s wallet can spend and which may be scattered among hundreds of transactions and hundreds of blocks.”
- Andreas Antonopoulos, Mastering Bitcoin
You don’t own any value. You don’t really “own” anything. What you KNOW is this secret number, which has a specific connection with the Bitcoin network. And since there are SO many numbers in the Bitcoin network (2¹⁶⁰ addresses), we can rely on this ridiculous probability and assume no one else will know that secret number.
So because you’re the only one that practically knows that secret number, you practically “own” that secret number, which means you practically “own” its specific connection with the Bitcoin network. And since the network is decentralized, you can use that secret connection to participate in the open network, bypassing borders, permissions, and ultimately trust.