Ah so now we have reached the point where litigation is threatened. Shut up or you'll get sued
I have no doubt that the pockets of top MLMers are deep, filled with money they've made from others.
In any potential legal case, the advice would be to do a cost benefit analysis. Costs are not just in monetary terms, but also in reputation. I think that the costs to an MLM regarding information that would come to light (including having to disclose average earnings and attrition rates) might be seen as too costly.
And as others have said above, nothing that has been posted on here is actionable. Mumsnet are careful about that.