That's how it's done in Eve Online, the money duplication scam is common there.

How it works is that the scammer announces in an area (usually the trade hub system Jita) that they're quitting and giving away all their money. They link to a webpage that (they claim)_shows all of their bank transactions, using Eve's API.

You send them 100K just to try it out, they send you back 200K, both transactions show up in the webpage. "Ha it works!", you say, sending them 1M, they send you 2M back.

Until at any point, they stop sending you money back. Their outgoing transaction shows up in the webpage, but ingame you never received anything. When you message them they go "must be a bug, I sent the money because look at my transaction log. Contact support, not my problem, the money left my account"

You'd think it just doesn't work, why would anyone fall for that, but plenty fall from it. Plenty of people try and outsmart them as well, making use of it to earn some money. But as another commenter pointed out, it can be like a game of roulette.

Nothing like being a n00b on Runescape and getting scammed of your entire bank by players "glow1:wave: Doubling Money" at the GE.

Iirc, ponzi schemes used to be welcomed on the bitcointalk forums. And people would sign up, knowing they were ponzis. Kinda like people playing roulette at a casino knowing they are playing a losing game but do it anyway for the thrill.

They're not always losing schemes (i.e. only some people lose), it just depends on if you're at the end or not. The reason they were encouraged is because people enjoyed gambling on how long they would last, and it was extra incentive to use BTC, etc.

In that scenario 10% per month would be a sufficient inducement and likely more believable given the volatility.