I would argue that the essence of Bitcoin is the monetization of proof-of-work. Proof-of-work has obvious value, as demonstrated by the fact that it can prevent

I would argue that the essence of Bitcoin is the monetization of proof-of-work. Proof-of-work has obvious value, as demonstrated by the fact that it can prevent spam emails, if emails require a proof-of-work hash over the message. Bitcoin's value is derived directly from this value, and works by trading ownership of tokens produced from proof-of-work. The problem is that not everyone wants to spend energy searching for hashes, so the solution is to create a database of coin units created from proof-of-work hashes, where the database itself is protected by proof-of-work. So, rather than everyone spending energy hashing on their phones, we exchange ownership of little bits of proof-of-work on the blockchain. As these proofs exist in limited quantities, they are, effectively, the same as the proof-of-work hash itself, such that sending someone a bitcoin amounts to transferring ownership of a small part of the proof-of-work that is the Bitcoin blockchain. It's not unlike the difference between a gold nugget and a stamped gold coin. A gold nugget has obvious value, but a gold coin is money because this value is easily recognized, by standardizing on coin size/weight/purity. They're the same thing, essentially -- the gold nugget and the coin -- but the standardization makes the difference between valuable and money.