Bitcoin is a network protocol for recording ownership of scarce digital tokens, in other words, bitcoin is a network protocol for recording the ownership of bitcoin. The protocol's value tied to how many people are using it, also the tokens themselves are a monetary commodity, so they have the monetary network effect where everyone wants to hold the thing that everyone else wants to hold. This is the same reason why people want green paper with numbers on it even though they can't do anything with it except trade it to someone else.