Earlier quoted context omitted.
Chungy is correct though. Bitcoin has absolutely nothing to do with "cracking sha256 hashes". Bitcoin hashes until the correct output is found. There are double hashes, but that is solely to avoid collisions and has nothing to do with determining the plaintext from a known digest.
>and has nothing to do with determining the plaintext from a known digest. So why'd you bring it up?
Cracking sha256 hashes implies trying to reverse a specific hash. There are literally thousands (millions?) of potential inputs that hash to a valid bitcoin mining block output. It's basically a race to find the first one matching the rules of the current block difficulty. The goal isn't to produce any one specific input/hash pair.