Gileswithachainsaw At first, try to steer this person in the direction of accurate information coming from outside of his/her group's Utopian 'positive' propaganda. Ask thought-provoking questions, particularly about what have been the quantifiable results of the particular 'MLM' this person is involved with?, and why key information like this hasn't been made publicly available? You could also ask if this person has sought independent legal/financial advise before joining, and if not, why not?
'MLM/Prosperity Gospel' Bots are lured inside these reality-inverting cultic groups by giving them the illusion they are making free choices. It is best to try to give them access to the truth and let them make a free choice to recognise reality and come out by themselves. Sometimes the more you try to reason with gung ho Bots, the more they will retreat into their groups bunker mentality, in defence of their self-esteem.
You could also try to persuade this person that the mark of a true friend, is someone who always tries to tell you the truth, no matter how painful this might be.