The only way you get rich through MLM is if you're an early adopter and you build a team of distributors beneath you.
You also need to be a fantastic salesman and put a lot of effort in. So many people see MLM as a 'second job' opportunity, but if you can't dedicate the same amount of time to it as your usual 9-5 then you're not going to make anything from it.
Some of the more genuine schemes, like Telecom Plus, work really well. Some of the others though, like the aloe beauty products just appear to be a massive scam to me.
I would echo Sam's views. I have seen it all over the years from various friends and acquaintances getting involved, from Amway through beauty products to the airplane scam. The person who comes up with the idea is usually the only successful one. Early Bitcoin miners is a good example.
I think this puts it into perspective (it is specifically about pyramid schemes but MLMs are not much different, they usually have a slower Level expansion):
Starting with the individual at the top, they have put no money in. They go an recruit 10 people who each pay $100. Those 10 people are then required to each personally recruit 10 people each bringing us to Level 3. This process could theoretically continue until somewhere between Level 10 and 11. With the world's population being just under 7 billion people you can see that the pyramid scheme would fail as there are just not enough people to recruit.
http://www.engineeredlifestyles.org/pyramid-scheme-defined.html