A Ponzi Scheme-its a fraudulent investment operation where the person who runs it takes money from investors and doesn't invest in anything, they just pay old investors back and keep on going in the cycle.
Bernie Madoff Length- He was able to keep it going so long because many people invested their lives in him so he had the amount of money to keep returning the initial investors money and also take some for himself. He also "invested" their money in stocks but he only reported that so people would think he was actually using their money for good.
Ponzi Person- A ponzi person is a very influential, very respectable person who is nice and is generous to others. Good business man who uses confidence to lure people in and make the operation seem exclusive.
The SEC did nothing about it after hearing multiple warnings about him because he was on the board himself and he had very influential family members who kept a deaf ear to the problems. His family probably bribed the SEC so that they wouldn't listen no matter how good the cases were put together.
I think Madoff did it because he thought he would get away with it but then it became too big of an operation and he couldn't just confess so he had to keep it going for as long as possible.