PKI is a silver bullet.

The weakness of the chain are human beings. For the same reasons the young coders are still making SQL injections, people keep bad practices for security.

Our human brain cannot store too much stress and secrets. So every human make shortcuts.

They forgot to check public keys and identity during key signing parties or accept to put in their ring of trusts people refusing to justify their identities.

PKI à la PGP like bitcoin is weak to local majority attack.

And human are still the weak point. Just target the vulnerable to take down the ring of trust.

Information technology requires better education. Not more expertise. Just the basics.