Problem there is that you're exposing the participants to volatility risk. if btc drops in price then people might be less likely to participate.
Many view bitcoin as a great new technology but its price is still too unstable to actually quote products/prices/prices in.
Quote in dollars, delivery bitcoin and everyone wins
my thought process is:
one large BTC pool. all transactions are feed into the pool. the order of the deposits dictate priority of withdrawal. Owner does not skim the transactions, only makes a large initial deposit and then markets the site like crazy.
Big assumption here is that he is running an "honest" ponzi operation.