0) Bitcoins were easiest to mine at the beginning => the creators & early adopters have a large number of bitcoins
1) New investors demanding a finite supply of bitcoins are increasing the exchange rate of bitcoins/dollar.
2) Early holders of large volumes of bitcoins can therefore cash in their bitcoins for a great deal of real money from new investors desiring to enter the market.
ergo, money shifts from new investors to the creators. (If the creators are smart enough to cash out. Which it seems they are, as Satoshi has disappeared. http://en.wikipedia.org/wiki/Satoshi_Nakamoto)
What you describe is a free market trading a limited resource; not a pyramid scheme.
In a pyramid scheme the wealth always flows up to the creator of the scheme, but the creators of Bitcoin can only make money by selling their own bitcoins - they don't get a cut when anybody else does.
1) New investors demanding a finite supply of bitcoins are increasing the exchange rate of bitcoins/dollar.
2) Early holders of large volumes of bitcoins can therefore cash in their bitcoins for a great deal of real money from new investors desiring to enter the market.
ergo, money shifts from new investors to the creators. (If the creators are smart enough to cash out. Which it seems they are, as Satoshi has disappeared. http://en.wikipedia.org/wiki/Satoshi_Nakamoto)