[bgibson]

True, but to nitpick it looks more like this:

Raw materials + innovation + labor + capital + time = waste byproducts + new utility added to the world in the form of convenient personal transportation that is sometimes (hopefully all the time) worth more than the sum of its inputs (profit). But all of those inputs get consumed in the process and one thing of value is the result.

Dual purpose mining consumes the inputs but creates two things of value, such that the miner is able to hedge, and to recoup their losses if the cryptocurrency fails. The fundamental problem is that reduces the cost the of attacking the currency, rewriting the ledger from some past point in history, should the miner decide to attempt that. In order for cryptocurrency to be secure, it requires that the miner be fully committed to the currency and that attacks are maximally costly and risky, unhedge-able (at least within the system, they can always short on third party exchanges and whatnot, but there's nothing the protocol can do about that), such that the miner's highest expected value is follow the protocol honestly.