This is a problem/misfeature with cryptocurrencies: You are never truly sure that you own any of it, until you spend/send it elsewhere. No matter what layers o

This is a problem/misfeature with cryptocurrencies: You are never truly sure that you own any of it, until you spend/send it elsewhere. No matter what layers of indirection(multi-party-sigs,bio-metric based encryption, etc) you put on it, at the end the private key has to come out in order to use it. With Gold, you see gold in your vault, you know it is yours. You see dollar in your pocket you can be sure you can spend that dollar tomorrow. You see a strip of paper with your private key in your pocket, there is no guarantee that you can spend those cryptocoins tomorrow. You see a private key(encrypted or not) on that Gold Bar, you do not know that it is truly yours unless you managed all steps of the encryption yourself. If you did manage all the steps of encryption yourself, then storing that information in a vault was pretty much pointless. I suppose one way these vaults can offer some sort of safety is that you come to them with your wallet, you make an onchain transaction into wallet whose private keys require both you and the vault to decrypt. This way both parties can be reasonably sure that the wallet stays unaffected until you come with a request to open it. Still a problem remains, you have to trust the vault to stick around and not lose their encryption keys. If you do not need vault's keys to open your wallet you've gained nothing by storing your keys at the vault. If you need the vault's keys you have to put your faith in vault not mishandling those keys, which means a single point of failure.