Not your keys, and the other half of that sentence

The slogan is not your keys, not your coins. It is true and it is half a sentence. The other half is: your keys, your sole and permanent responsibility, with no reset link, no support line and no recourse.

Both halves have killed real money. Exchange failures have destroyed billions. Lost seed phrases have destroyed a comparable amount and nobody can even count it properly.

The three models

Custodial. An exchange or a broker holds the keys. You have an account balance and a legal claim. Convenient, recoverable if you forget a password, and dependent on the solvency and honesty of a company. A regulated custodian that segregates client assets is a genuinely different proposition from an offshore exchange that commingles them, and the 2022 failures were overwhelmingly in the second category.

Self-custody. You hold the keys, typically on a hardware wallet, with a seed phrase backup. No counterparty. No recovery. The failure modes are yours: a lost backup, a house fire, a phishing site, a malicious signature, and the inheritance problem nobody plans for.

Multisig and shared custody. Multiple keys, a threshold to spend. Two of three is the common setup: one at home, one in a bank box, one with a service. It removes the single point of failure in both directions, and it is more complex to set up and to explain to a family member.

The five ways self-custody actually fails

Note that only one of these is theft by a hacker.

Lost backup. A phrase on paper in a drawer, thrown out during a move. Steel plates exist for exactly this and cost less than a dinner.

Single location. Backup and device in the same house, which burns or is burgled together.

Phishing and blind signing. The largest active threat. A convincing site asks you to approve a transaction you do not understand, and the approval is irreversible. Reading what you sign is the whole defence, and hardware wallets that display the transaction clearly are worth paying for.

The photograph. A seed phrase photographed for convenience, synced to a cloud account, compromised years later.

Death. The holder dies and nobody can find or understand the backup. This is common, entirely preventable and almost never planned for.

The practical setup most people should use

Split by purpose, not by ideology. A small amount on a regulated exchange for trading and for the fiat on-ramp. The long-term holding in self-custody on a hardware wallet from a reputable manufacturer, with the seed phrase on steel in two separate secure locations. A written instruction for heirs, held with a lawyer or in a sealed envelope, describing where things are without containing the phrase itself.

For institutional or very large holdings, multisig with a qualified custodian as one of the keys is the standard answer, and it exists precisely because neither pure model is appropriate at scale.

What regulation changed

MiCA in Europe and equivalent rules elsewhere now require licensed service providers to segregate client assets from their own and to hold them so they survive the provider's insolvency. That is the single most important consumer protection in this market and it directly addresses how the largest failures happened. It does not make a custodian risk-free; it makes the risk assessable.

What to watch

Watch for proof-of-reserve practices that include liabilities, not just assets, because reserves without liabilities prove nothing. Watch social recovery wallets, which try to make self-custody survivable without a seed phrase. And watch inheritance products, which are the least glamorous and most needed part of this whole field.