“By default, bitcoin kept users’ currency in a digital “wallet” on their desktop, and when bitcoins were worth very little, easy to mine, and possessed only by techies, that was sufficient. But once they started to become valuable, a PC felt inadequate. Some users protected their bitcoins by creating multiple backups, encrypting and storing them on thumb drives, on forensically scrubbed virgin computers without Internet connections, in the cloud, and on printouts stored in safe-deposit boxes. But even some sophisticated early adopters had trouble keeping their bitcoins safe.”