You are correct, the more specific term that applies to virtually all MLMs is they are illegal pyramid schemes, and many of those are RICO frauds, owing to the tool scams they operate. I was answering the question in the context of the question, and I consider Ponzi schemes, illegal pyramids, and RICO fraud as subsets of the more generalized term, scam. Now that we have those definitions clarified, what are we going to DO about it?