+1
It was good to read a couple of thoughtful posts on this subject, without red 48 point font or "I get payed out my .00000001 is be good sceme live long time" contributions.
Just a couple of points:
"Ponzi games" cannot be considered legit (overused word) imo until there is some way of proving that the early (profitable) deposits in a round do not come from the operator of the scheme. I can't see how this can happen, so they cannot be compared to conventional gambling with 'provably fair' and house edge systems.
The comparison with governments providing social benefits by kicking the deficit can down the road in the form of future unfunded liabilities is not valid.
I am no lover of the world's current financial system which is why I am interested in possible alternatives like bitcoin, but there is a huge difference between political decisions taken with few socially acceptable alternatives and deliberately engineered fraud designed to benefit the perpetrator only.
You are correct that proving the operator of a Ponzi site hasn't put his own deposits in first could be hard to prove. I agree completely that is an issue. It wouldn't be in their long term best interest, but most scammers are not long term thinkers.
However, at the same time, many of the so call proofs accepted for things like dice games could be cooked by a skilled programmer. Open source isn't a protection either as it may not be the actual source for the program running. There are many backdoors. However that type of exploit takes a lot more skill than a Ponzi operator stacking the deck. The counter point is I don't see how any gambling game can be really made provable fair.