Private keys (secrets) makes sense for securing time-bound communications of relatively low value.
Private keys (secrets) makes absolutely no sense as a "store of value".
Once the secret is out, or recreated, it loses its value and utility.
Blockchain technology is here to stay, as a niche player in distributed computing.
Blockchain technology is just a tool though, means to ends, not the end itself.
There's no way technology can or should be the final arbiter for humanity.