Which one in particular? most of what I see are:
- Ponzi's, some more blatant than others.
-  mining bonds. Sure, they pay high yields, and are not ponzi's, but they lose value much faster than the dividend makes up for.  If you create a derivative that passes on the dividend of those mining bonds but doesnt account for their free fall market price, you effectively do have a ponzi. This is basically what Diablo did with DMC and see how thats going.