Bernie Maddoff也没有宣称过２０％，有的时候就应该让他们去跌一下

Madoff's annual returns were "unusually consistent,"^[48] around 10%, and were a key factor in perpetuating the fraud.^[49] Ponzi schemes typically pay returns of 20% or higher, and collapse quickly. One Madoff fund, which described its "strategy" as focusing on shares in the Standard & Poor's 100-stock index, reported a 10.5% annual return during the previous 17 years. Even at the end of November 2008, amid a general market collapse, the same fund reported that it was up 5.6%, while the same year-to-date total return on the S&P 500-stock index had been negative 38%.^[13] 

https://en.wikipedia.org/wiki/Madoff_investment_scandal#Modus_operandi

去看看关于ｐｏｎｚｉ　ｓｃｈｅｍｅ的书，就知道了。