Crime, unfortunately.
Money laundering is done to "clean" illegal profit (hence the name). Say your business sells a bit of a meth precursor to a high school chemistry teacher for more than it would legally. You need a way to explain the extra money, and a way to explain where than precursor went.
Things that this won't protect: sex work, drug dealing, hawking stolen goods. Things this will protect: owning a building where you were unaware every tenant was a sex worker, running logistics company that some bad apples on the exact same routes always carried packages of cocaine, or selling artifacts smuggled out of foreign countries.
Normally I'd say "that's not how it works" but given the shit we've seen it might in fact work