I don't understand why one would need multiple drives then. Seems like you could earn the coin, sell it for USD, erase the drive, and earn another coin with the same disk.
What prevents this?
What prevents this?
Once a farmer wins a block it's theirs, the same way it works with bitcoin. The reward is tied to a public key, not the original storage. Just like in bitcoin once a miner wins a block they don't need to continuously prove that they have x amount of hashing power in the future.
You can learn more about the details of the blockchain and algorithm here: https://www.chia.net/greenpaper/