Yep, bitcoin fits the definition of a Ponzi scheme.
Those vested into the Bitcoin system don't want it labeled as a Ponzi system.
Everything about it smells like a Ponzi scheme, however people keep defending it as not being a Ponzi. Those in the Bitcoin market need it to remain 'not a Ponzi' just long enough to make a few bucks off of it. That, and I think they morally don't like the idea that they themselves may be involved in scamming someone.
Do I think that there are honest well intentioned people that are in the Bitcoin market? Yes
But learning a little of the background into how Bitcoins work before 'gambling' on the IDEA of an electronic currency would be much wiser.
The bitcoin idea, while novel and possibly noble, is flawed. The incorporation hyperdeflation is simply too risky and no better than the current Federal Reserve monetary system we have now.