That's an inherent risk when your assets are managed by an external party. Cash in a bank is seemingly always accessible because its "liquid." Liquid means it is a ledger that almost everyone uses.

If no ledger is available to show how much the bank can give you when you ask for it, OR the bank no longer HAS that cash on hand - they can't give you that asset.

Every asset requires a special ledger. Destroy that ledger or that asset... the asset is effectively gone.

We know exactly what happens when these situations occur. If you obliterate a house, there better be a ledger showing you purchased insurance in the case of loss, otherwise you are SOL. If people lose faith in a bank, and a bank run occurs - the cash gets exhausted and people are SOL until cash comes back.

If all of your physical and cash assets are stored in a physical vault, and the vault is destroyed, those assets are gone.