MLM schemes attract people not just because they promise quick money. They support this idea with social engineering. There are meetings where enthusiasm and fervor is whipped up. They give them arguments to counteract nay-sayers. They may even encourage them (as in your example) to cut off contact with nay-sayers as being a source of negative energy. These are common brain-washing techniques.
For more information about brainwashing, this article might be helpful. It talks about hypnosis, but if you just substitute those rallies for individual hypnosis, it’s the same thing. This is another site that explains MLM techniques. I’m not sure these offer any help for deprogramming MLM adherents, but they do help you understand it better, and if you can get your sister to read them, she may understand better.
The only way she can make money is if she got in early and she spends all her time doing it, and she has no compunction about recruiting friends and relatives. If she’s been in it three years, and she’s doing these things, then perhaps she’s in early enough to make money.
To deprogram MLM people, there are a number of steps in this website. Unfortunately, to me they seem to all involve people reading about the problems of MLM. If you can’t get someone to even consider reading these things, you’re SOL. Your problem is with reconnecting with your sister and getting close enough so she will read the materials.
I suppose you could try to appear to have an open mind about these things. Tell her you’d like to give her a chance to make her case, and you’d like to make money, too. Then bring her these articles, and ask her what’s wrong with them, because they have you concerned. You think they must be lies, but you don’t understand them.
Or some such nonsense. The articles will definitively show her the delusion of MLM, but in order to get her to read them, you do, as you say, have to reconnect with her. I suspect that in the end, you’re the only one who can figure out how to reconnect. Whatever you do, I don’t think kidnapping her for deprogramming is ethical, even if it works (and I’m not sure it does). I think you will have to find her other ways to get what she needs (affiliation—a sense of belonging, excitement, passion, etc). These are things we all need in our lives. If you can replace MLM with other things that do this, you might be successful.