After all bitcoin is just a ponzi scheme, you profit as long as there are greater fools who buy your coins at a higher dollar-price.
From an idealist point of view a coin should be free and instead the coin should gain it's value as an IOU for the delivery of goods or services, for example gold.
Wrong.. Bitcoin has nothing to do with Ponzis whatsoever. Read up on Ponzis and don't stop at the wikipedia headline. MtGox however could be much more similar to what you are talking about if accusations would prove to be true. Still wouldn't count as Ponzi though. But if they took traders' deposits to pay out withdrawals or traded on their own account (as a bank was doing in the mid 90s, true story - see the movie rogue trader with Ewan McGregor) and artifically helped to push up the bitcoin price, yeah it's close to a Ponzi.
None of this has to do with Bitcoin as such though. There are now lots of other big exchanges and if Gox should go away, Bitcoin will continue to prosper.