Why ONLY Madoff charged in largest fraud/crime in US history worth $187Bil over 24 years with tons of help?

Does it makes sense that the only conviction and sentencing is of a 71 year old man to a minimum security club Fed prison? All his children, his brother and dozens of people were 'working' with him since the 80's on this ponzi scheme, not one penny was ever invested in any way, all they did was collect money from investors and spend it however they wanted to, even the office clerk owned several mansions, so why is the fed/sec so sympathetic to this guy and letting everyone go free??? Please help me understand! His wife will keep millions in cash for her 'cooperation'. Is this like a joke?? Of the $187 billion only about 2 billion have been recovered, the rest is of course hidden with his various family members and employees unless aliens took them from space. So what gives? Why do white collar criminals not get punished?