So it replaces regular energy expenses with instead very large up front capital investments in hard drives which is no more green - hard drives don't appear out

So it replaces regular energy expenses with instead very large up front capital investments in hard drives which is no more green - hard drives don't appear out of thin air - and adds in wacky incentives/vulnerabilities as now anyone with large storage space can enter at any time with the equivalent of enormous hashpower to crush the network without any economic penalty as they can simply go back to using their hard drives for storage afterwards without any significant expense incurred (by design).