Short of selling organs, there aren't really any unethical but not very illegal ways to make lots of cash quickly. That's because if there were, people would already be doing it. There is no magic thing to do that will earn easy cash that isn't illegal. Even selling drugs isn't something you pop down to Walmart to pick up and start doing. You need a source, contacts, customer base, and means to handle the money. That doesn't just happen overnight and I don't think there are "Let's start dealing" conventions out there.