Ponzis and similar schemes, of course, you may earn a lot if you know when to withdraw (prior to their running with the funds of the users). Do not tell me it is not exciting to have to take the decision of either stay one more day/hour/minute or withdraw?
Just to clarify, I am not advising anyone to invest in such "business models" (as I am not either suggesting anyone to gamble).
I do agree on this because I am investing and risk-taking on ponzis, they are really more profitable than gambling IF you know how get used into it. I just don't find it fun compared to gambling on casino sites.
Eventhough I am playing and earning profit with ponzis, still, I do not recommend it as most programs tend to collapse/scam earlier than expected.