Worse case scenario: the financial system can nullify or block your client's assets.

No one can do that to his or her cryptocurrency.

Also, a good way to help your arguments is explaining the digital applications for blockchain technology: smart signature (bye bye DocuSign), advertisement on Nostr (Zap me and I will talk about his or her products or services; create a banner and pay someone to boost it now and then). Just a couple of examples.

Use private key and public key management with specific authenticators for different and exclusive digital or physical products and services.