He actually means that it has matter properties that make it valuable.  But no matter, it seems not a reality. It's just in his mind.
Bitcoin exists with protocols. It's all there is and we just gave it a value because someone started it with pizza and because there is a property or a characteristic of Bitcoin to be rare which we all know only has 21M as total supply, its value increased. Its how it becomes valuable.

If there are other minerals that we could consider to be valuable and could be used as the money we might actually be using it but then history will once again repeat because humans will always bet and inflate and then once again create banknotes as it had been done in the past.