[greggsy]

People using ‘cold’ hardware wallets are air gapping crypto to a degree. It’s really just offline key storage, which is as old as IT itself.

They’re not mainstream because crypto isn’t mainstream outside of the crypto-bro community, mainly because it’s inconvenient for both parties trying to make a sale or purchase.

I’ll tell you what is mainstream though: chip+pin and nfc+bio, which in combination with a ‘good enough‘ key storage and interrogation regime, are a decent balance between convenience and security.