Mining hardware hashes SHA256(SHA256()) of the block header. If anybody does that to crack some passwords, they do it at expense of not earning bitcoin. If they

Mining hardware hashes SHA256(SHA256()) of the block header. If anybody does that to crack some passwords, they do it at expense of not earning bitcoin. If they want to earn bitcoin, they have to hash block headers instead of passwords. Intermediate non-valid hashes are thrown away, but all of them hash almost the same data: header with some nonce value.