When I was an Amway bot I was told I would get nowhere unless I had the tape of the week and the book of the month. All at a cost, of course. Then there were the monthly rah-rah sessions at some cheap hotel or conference centre, and the weekend dos. Again, these cost a fair bit of money.
There was a LOT of pressure to attend all the available things, even though they were exactly the same each time. The time it took just to do that was horrifying. Then there was the time spent listening to the brainwashing tapes, and reading the 'you can do it' books.
It's a bit like living with a controlling partner; only allowed to do certain things, and other things (like cooking a decent meal, or seeing friends socially, or having any fun at all) are Very Bad, and the reason why you have not succeeded.
When the business was investigated it was the sales of these motivational items which were under scrutiny, and it seems that's where the money came from to fund the top peoples' lifestyles. Reading between the lines of things I saw/heard later, it literally was only the top two couples who ever made any money.
I would not be very surprised if similar is happening in all the MLM rackets.