I've heard this argument before. I don't agree. It obfuscates the reality of the proposition. bitcoins are a by product of the proof that energy was expended by arriving at a valid nonce. Provided bitcoins remain limited to 21 million, the cryptography securing the utxos is not corrupted, and energy needs to be expended to arrive at a valid nonce for every confirmed block, bitcoins will have value that others will exchange goods and services for.