It was found not to be "illegal," and if it were a true scheme, it would have collapsed decades ago.
DeVos, however, does have a Canadian conviction for tax evasion; that won't help.
Well, they primarily sell marketing materials and make most of their money through fees paid by the reps and in buying the kits rather than in the actual sale of products, and most of the products they do sell are to the reps themselves. They don't really truly have a product, they just resell things from others and people pay them to hear presentations about how rich you will get if you can sign up other reps and to convince you that you are a loser and a quitter if you don't stick with the program even if you aren't making any money at first. It's a thoroughly dishonest way to make money.
As a general rule, any job in which you have to pay money in order to get hired or in order to keep your job is a scam.
The courts do not agree with that assessment. I do not sell it, but I have used some of the products and have been happy with them.