Crypto investors are turning to Military grade vaults to safeguard their Keys. While some prefer to know the Keys by heart, some have their crypto stash in physical dedicated crypto wallets like Trezor and pay big money to have them stored in Nuclear sheltered safe vaults. Take for instance
Swiss Crypto Vault who offers Nuclear sheltered vaults to crypto investors. if you had 2000 bitcoins what options would you pick?
Using vault to lock a key is also known key within a key. Which is also good to keep crypto (Bitcoin) key. But device is unpredictable which can be spoiled or damage at anytime. There are many places one can keep or store his Bitcoin key or password. You can store your password in your heart or brain, a sheet of paper, note book, email, your wife or daughter, another phone, desktop, laptop (PC) etc. But I believe the best place to store crypto currency (Bitcoin) key or password is your brain and a jotter. In the jotter or note book, if in case you forget the key in your brain, you can easily get it the hardcopy store (jotter or note), to access your wallet.
In addition, you can also tell your son, daughter or wife so in case you pass away, they can withdraw the funds from the wallets and use.