Good point, well made Clarinsgirl
Sadly once people have spent money on something it gets even harder to convince them that they're wrong because they've made the investment. We all like to think we have made rational decisions - especially those that have cost money.
Those that do realise end up feeling like fools. I think we need to emphasise that they are victims of a very clever, very manipulative fraud and it's not their fault.
I was a victim of a more blatant fraud once. I had to call the police and I was crying down the phone as I felt like such a fool. The call handler was lovely - she said "you're not an idiot you're just a nice person, and you expect others to be the same. Most are, but some people will take advantage of that."
And therein lies the whole MLM phenomenon.