Unlike dollar bills and gold, you can own and move bitcoin without putting it in your pocket. You can walk across the border with it. You don't have to declare it for the crime of carrying more than $10,000 like you do with cash.

You can't store lumber or gold in your head in a brainwallet or in a securely-encrypted digital file. And the lumber or gold ownership relies on a legal authority to recognize and protect the ownership.

"brainwallet" might be my cyberpunk thing of the week ^^