99% of people who "buy in" to an MLM lose money.
The only people who make money in MLMs are the people who FOUND the things - and their first level underneath in the pyramid.
A month doesn't go by without one of those "great business opportunity" companies being sued into oblivion. Look at their financial reports - most are required to be publicly available.
*No one* wins in an MLM. And if you have any friends who "swear by their product" - the products are frequently either terrible, toxic, overpriced, or all three. Usually all three.