There is another significant distinction between Bitcoin and a Ponzi scheme. In a Ponzi scheme, you put money into it with the expectation of getting more money out than you put in. In Bitcoin, you don't do this -- or rather, nothing in Bitcoin will tell you that you can.
If you can point to the bit of Bitcoin that attempts to give you this expectation, then great: please do so. However, please don't point at a person pulling a scam involving Bitcoin -- that would be like pointing to Charles Ponzi to explain why the US dollar is a scam. Similarly, please don't point to all the speculators: they are essentially the same thing as Wall Street day traders, and they don't make the US dollar a scam either.
Bitcoin is a payment network. To make a payment using Bitcoin, you buy some bitcoins on an exchange, then you send them to the seller, who sells them on an exchange. Where is the scam in all this? You paid your $x, the seller got his $x. That's not a scam, that's mission accomplished.
Bitcoin is in fact a clever Ponzi scheme, in that the founders can profit without even being identified. (It makes sense that they don't want to be identified now, doesn't it?)
Bitcoin's fundamental problem, and why it has all the hallmarks of a Ponzi scheme (if it walks like a duck...) is that it is a deflationary currency by design due to the deliberate reduction in the supply of bit coins over time and the consequent artificial scarcity. No, being able to divide bitcoins into smaller parts does not solve this problem! It remains deflationary.
One can assume one of two things about the designer(s) of Bitcoin:
a. He/she/they did not understand economics well enough; or
b. He/she/they did understand economics well enough.
If (a), then the dangers of a deflationary currency (which encourages hoarding and not spending / investing) were unknown to him/her/them.
If (b), then these consequences were understood and were therefore considered desirable.
Assumption (a) makes this an accidental Ponzi scheme, but a Ponzi scheme nevertheless. Assumption (b) makes this a deliberate Ponzi scheme. Either way, the net result is the same. The original miners (which will have included the founders) make a whole lot of money. Late entrants provide them the money and in so doing lose theirs.
Bitcoin cannot be used as an alternative currency because it is deflationary. End of story. If you think it can be, then please provide your new theory of economics, and we can all go back onto the gold standard.
I suggest getting out of Bitcoin now.