A question from Yahoo! Answers:

Why does Network Marketing get such a bad rap?

For the same reason large corporations do; it is a setup where diligent work by many seriously enriches a few who sit at the top of the organization. In many respects, it is even worse than working for “da man”; there are no wages, and you are expected to “invest in your business” (translation: buy a certain minimum amount of goods for resale).