Nobody truly owns any bitcoins..because the ownership is only established when you are able to apply a correct private key in a "send" tx (via hardware device or something else), albeit validation of the private key (at some other point in time) is possible. Before that, it is all allegedly. This is in principle, of course.
Nonsense. Of course you own your bitcoins as long as you and you alone possess the private keys to your Bitcoin addresses. Nothing
else is required.
No hardware devices are required other than mnemonic devices. It's the corollary to NYKNYC...
your keys, your coins. No one can take them away from you, no banks, no governments.
Contrast that to less finite asset ownership such as fiat currencies, "precious" metals, real estate, art, antiques, etc.
The only assets as valuable as Bitcoin are the relationships you establish with people.
That's right, as long as the keys are yours and only yours, the bitcoins remain yours as well. But, in addition to the options for losing keys mentioned by Biodom, there is always an unexpected hacking option. We can recall the story that happened a few months ago with Libbitcoin, where key generation was carried out with insufficient entropy, as a result of which the keys generated in this way were especially vulnerable to hackers. This way, you can be confident in the safety of your keys and still face the loss of your bitcoins. The probability of this is almost zero, but still not zero.
https://www.coindesk.com/tech/2023/08/14/disappearance-of-900k-puts-focus-on-vintage-bitcoin-project-libbitcoin/Even if other assets look less attractive, this does not make Bitcoin ownership absolute. Biodom beautifully said, "Nothing is guaranteed, but bitcoin "mechanics" is probably one of the closest approximations to that ideal." Very close to ideal, but not absolutely.