[nradov]

We have had widely used public key infrastructure available in database products since the 1980s. Perhaps you weren't paying attention?

Cryptography obviously has use cases. Real customers have been paying for it since long before the advent of digital computers. That has little to do with the scammers, grifters, and ideologues pushing cryptocurrency schemes.

There's not much novel about blockchains. It's a clever bit of mathematics, but so far no significant commercial value. You should read the NIST overview.

https://csrc.nist.gov/publications/detail/nistir/8202/final