Don't know who is buying the PPC but I know why:

1. It is not yet widely understood that the inflation rate of PPC is dropping very quickly. Annual inflation in coin supply is now under 18% compared to Bitcoin's 14%. PPC inflation falls with a rise in difficulty and difficulty is rising very quickly because of ASICs. This means the inflation rate of PPC will probably fall below that of Bitcoin within a few months, and then continue to plummet, making PPC very scarce.

2. PPC uses Proof of Stake for security which is simultaneously orders of magnitude cheaper and orders of magnitude more secure than the Proof of Work.