Sure. I was caught up in this massive thing that overtook my life where I felt like anyone not in it was an idiot. I tried telling everyone, knocking on their doors, but they didn't want the miracle cure to life that I had for them. Either way I kept giving of my time and energy and money, never got anything tangible in return other than a feeling of superiority knowing that I had the secret to happiness, while those at the top got money and I was living a life of poverty and servitude slaving for a fairy tale that I bought in to. I might still have an old box of product around somewhere in the basement.
Other than that, sure, I saw things like vitamins and supplements, legal aid, telecommunications, and other such mlms.