Bernard Madoff is expected to plead guilty today to multiple counts of fraud, which will leave him facing a lifetime in prison. There are lots of questions about how he perpetrated his epic Ponzi scheme. Many remain convinced that he had some accomplices who ought to be prosecuted. But perhaps the biggest mystery is, "why?"

Why did he do it? What motivated him? He was already rich and revered on Wall Street. Why did he need more? The answer lies in his psychology as much as anything. Perhaps it was that classic need to prove to himself that he could outsmart the world. He certainly did that until he fessed up to his sons. 

For more:
- here's a Reuters article

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