Why do you think that you can&#x27;t lock bitcoins in a vault? You just put your private key on a disk or flash drive or print it as a QR code and then lock that in a vault. It&#x27;s called a cold wallet. That&#x27;s what huge holders of bitcoin do to mitigate the risk of a security breach. They keep a small working amount of bitcoin in a hot wallet and keep the rest safe offline.