the problem is that you're responding to a substantive criticism by identifying a formal distinction. to most people making the claim, it doesn't matter whether bitcoin is literally a 'ponzi scheme' in some platonic, classical sense. some even recognize the distinction and point out that it operates as if it were a ponzi scheme, albeit through a new and interesting process. for example, eric posner's article at slate does this: http://www.slate.com/articles/news_and_politics/view_from_chicago/2013/04/bitcoin_is_a_ponzi_scheme_the_internet_currency_will_collapse.html

i agree that mt. gox's speculations about the price are irresponsible, ill-informed, and essentially fraudulent.

there are many such similar claims in the community. even in this thread, there are ill-informed claims that assume, as background, that the natural progression of the price of a bitcoin is to climb indefinitely:


when nobody is buying and people are selling, the price will fall. that is true of any investment scheme, ponzi or not. a falling price is a falling price. you can only call it 'stagnation' if you assume the natural state of the price is to rise exponentially. there is literally nothing in the world that has that natural state forever.

the bitcoin technology is itself not a ponzi scheme or any kind of scam. the promotion of bitcoins with language like 'it always goes up' or 'get in before it's too late' is, as posner argues, essentially indistinguishable from a ponzi scheme even if there is no organized head and even if the beneficiaries are distributed. the speculatory value of a bitcoin depends on the hope of selling it to others at a profit even though the coin itself, unlike a stock or bond, never generates its own productive return or dividend. (for the record, yes, gold is the same way. it doesn't matter.)

i also think there is a decent chance that mt. gox are actively manipulating the market to bolster the price. the only way to know for sure would be for them to submit to a third-party audit or for enough people to stop using them. they have consistently marketed bitcoins to the public with very scammy language.

it's remarkable how quickly people forget: if it sounds too good to be true, it probably is.