Bitcoin mining isn't a get-rich-quick scheme, nor is Bitcoin itself for that matter.
Damn.
We need a pyramid cryptocurrency stat.
There have got to be one or two good ways to start a Ponzi scheme with Bitcoin...
Start a reverse Ponzi scheme where the guys who get in first receives less than the guys they recruit. If they want to continue to get paid, they must recruit more members, and the members whom they recruited don't receive the higher reward until they recruit X. Call it the RMLPS (reverse multi-level Ponzi scheme): Turning your network upside down.
(tired and going to bed, so if the above doesn't make sense, this is why)