How do you put bitcoin in a bank vault?

You create your seedphrase - the famous 12/24 words, print them on a piece of paper and put it in the bank vault. Ideally some sort of fireproof container/envelope around it, and if you plan on long-term storage rather write them down manually with long lasting ink pen.

He’s saying put regular money in the bank vault, why complicate with crypto.

You buy a little bit of titanium sheet and some alphanumeric punches and you punch your seed phrase into it. It won't matter if the bank burns down or gets flooded, your plates will be fine.