Back in the early days of Bitcoin a guy mined up 7,002 bitcoins.
He put 'em in a wallet on an Ironkey USB device and forgot about them, they were basically worthless at the time, however 7,002 BTC has a current value of around $220 million.
IronKey USB drives are encrypted, you have to enter a password to get in to the data, they also have a self-destruct mechanism; put the wrong password in 10 times and the device irrevocably destroys itself.
He lost the piece of paper that he wrote the password down on, and has tried 8 times unsuccessfully to unlock the device.
I've gotten second hand anxiety for the guy just thinking about that situation...
https://stockhead.com.au/tech/a-german-programmer-has-2-chances-to-guess-his-ironkey-password-or-hell-lose-280m-in-bitcoin/