For more information, John Oliver did a fantastic segment about the horrors of MLMs. The 2016 documentary, Betting on Zero, investigates the allegations that MLMs are nothing but legal pyramid schemes. This article also does a wonderful job of breaking down the reasons why MLMs are doomed to failure. I encourage anyone who is thinking about signing up for an MLM to watch these.
The legal distinction between MLMs and traditional pyramid schemes has been characterized by many authorities as a legal fiction. Jurisdictions that retain a legal distinction between MLM pyramid businesses versus illegal pyramid schemes retain said distinction on two key distinguishing features: 1) that MLMs always encompass the sale of actual products/services, while traditional illegal pyramid schemes ordinarily do not (though sometimes they do), and 2) that climbing an MLM pyramid is overwhelmingly statistically improbable (especially to its highest participant levels) but not theoretically impossible, whereas climbing a traditional illegal pyramid scheme is both statistically and theoretically impossible.