I think those that make money off it have to be very motivated, very good at sales and really believe in what they are selling
The ones who make money, proper money, don't sell product. The ONLY way to make money in MLM is to recruit (sell the “opportunity”) and build a large downline. Selling product will only really bring small amounts of money and it’s not consistent and it’s often saturated - where I live every second post on the village website is an Avon seller and in my road there are 20 houses and three Body Shop sellers. Those who recently joined may think they’ve entered a viable product selling business because they have only just tapped into their social network. Therefore they will get initial purchases but that tends to tail off pretty quickly and that’s when the pressure to recruit starts to be felt. This business model requires replenishment at the bottom and a constant stream of recruits all paying their money and buying product (who is the real customer?). The MLM doesn’t care if two distributors live next door to each other, that’s two more customers for the MLM.
An upline doesn’t make money on what the downline sells to outside customers, they are rewarded on what the downline buys. So if you consider that then you can see the exploitative potential. So many distributors get caught in a purchasing trap to stay “active” to achieve targets and “promotions” (who gets a promotion if it’s supposed to be their own business?!). That situation of buying product to hit targets is known as “garage qualification”, in other words a distributor with a bedroom and garage full of their purchases - the MLM doesn’t give a flying fuck whether the distributor can sell it afterwards which is why you see so much product on eBay etc and why your friend who sells Younique gives everyone Younique EVERY Christmas and birthday.
As for success, or what looks like success. There is about 1% who are very successful in MLM. Often the ones held up as successful are not all they seem. Forever Living has its poster girls and boys who were part of the 1% and who received six figure sums for a couple of years. These people are still wheeled out to entice people and yet many are no longer receiving much income at all; many are barely trading, some are keeping up a front by living off large directors loans, one is bankrupt, another has just come out of a bankruptcy order. It’s an illusion but sadly, due to COVID employment instability it’s pulling in even more people and 99% will lose money. Take a look at the MLMs’ own Income Disclosures to see how many distributors make nothing (and it’s actually worse even that those IDs indicate)
Have a look at the BBC documentary The Secrets of the Multilevel Millionaires which is on iPlayer. It’s a massive scam.