The Brains Trust, page-3850

@Orwell, I sympathise with your situation as many years ago I went through a similar situation with my partner at the time (now ex thankfully). The "network marketing" scheme was one of the most ridiculous that I had ever encountered and placed a greater emphasis on the individual to sign up "sales associates" as opposed to actually moving product of which they were required to buy a significant amount themselves (which far outweighed any sales she could muster).

Anyways, my only advice is to keep your interaction private and personal (so as to avoid embarrassing her) and tailor your strategy to the audience.
Initially I was fairly blunt and honest -and somewhat rude- about the stupidity of it all and she took this as a personal slight which made her even more committed to succeeding which subsequently led to her spending more to "upgrade her status" as well.

Fortunately I got some decent advice from a close friend of mine who is somewhat of an idiot savant i.e borderline illiterate but can fix anything with his hands and occasionally assesses a situation to perfection and espouses something extremely philosophical.
Anyways, I sat down with her, took the emotion out of it and together we analysed the "business" to the best of our abilities with the information available. Looking at it logically and rationally she understood that it was designed in such a way that unless she was the originator (top of the pyramid) the expected returns that they spruiked would never manifest and were still far than the minimum wage for the hours she put in.