A Coldcard entropy bug believed to have gone undiscovered since at least 2021 has prompted Bitcoin self-custody advocates to recommend multi-vendor multisig wallets, which require signatures from multiple key pairs generated by different providers. The incident was linked to the loss of more than $100 million worth of bitcoin, mostly from single-seed wallets, while Casa CEO Nick Neuman claimed that 233,000 bitcoins moved to safety in response. The episode has challenged the long-standing preference for single-signature custody, in which one wallet generates and controls the private key pair. Multisig (a wallet requiring multiple signatures to authorize spending) can reduce dependence on any one hardware-wallet manufacturer and may also improve resilience against theft, phishing and social-engineering attacks. A typical arrangement could use keys from a Trezor Safe 7, a Ledger Nano and a multisig provider’s recovery key, with a 2-of-3 threshold. Other structures include 3-of-5 setups, multi-jurisdictional arrangements and time-locked recovery keys. The trade-off is greater operational complexity: users must safeguard enough signing keys and also retain the multisig script or template needed to recreate the wallet’s spending conditions if the provider becomes unavailable. The discussion underscores the importance of building a personal threat model that weighs the likelihood and potential severity of user error, lost backups, forgotten passwords, theft and software or hardware failures.