I actually think the failure rate is a solid 100%. I guess it depends on how you define success. Even if you manage to build a large enough pyramid underneath you to remain profitable you aren't any more successful than Bernie Madoff IMHO.
The Bernie Madoff case is prime example of how the agencies designed to protect people failed. The SEC seems to have been out to lunch for near a decade despite being given indications that something was wrong.
The one good thing is the case had embarrassed the SEC enough to look into some other situations more closely. The bad thing is there may be many more of these thngs out there ready to blow up in everyone's face.