The Coinbase Vault is a pretty great idea, but the problem (in my opinion) is the timelock. There was a point when I urgently needed some coins that were locked in the Vault, and iirc they made me wait 48 hours, which is a major pain in the ass. I would also recommend that you steer clear of Coinbase altogether - they are a very shitty company and have banned my account for a rather trivial reason. Just don't use them. Get a private key and lock it in a fireproof safe, there's your vault.