as i understand it one new victim buys btc and sends them to MMM which takes some of the BTC and sells them to pay the older victims
so afterall it should lead to revenue but not necessarily buy pressure
Does he pay out in money? I would expect him to pay out in bitcoin too, for the same reason that he takes bitcoin.
Many of the victims will surely re-invest all their payouts in the scheme, and then add some more money.
Thus the net effect of the ponzi should be to lock up increasing amounts of bitcoin in (a) the members' accounts, (b) in transit, and (c) in Mavrodi's deep pockets.
You may be right in terms of net amount. But his scam is subtler than that. He never takes in bitcoin or cash directly, nor pays it out. Instead, it is a decentralized ponzi. It involves individuals making requests for contributions, and other people fulfilling those requests directly, using bitcoin or bank transfer.
However, the twist is that before you make a request, you have to make a contribution to someone else who has made a request. And the amount of money you can request is tied to their own virtual currency, Mavro. You earn Mavro by making a contribution, and then that Mavro grows over time, and you can accelerate that growth by doing "tasks" (why appear to be social networking, i.e. growing the scam). I think you may also to be able to "by" Mavro.
Presumably, the way MMM makes money is either in the selling of Mavro, or there is some kind of monetization of tasks.