Coercion. Both depend, or in the case of Maddoff, depended, on being able to get new contributors into the scheme in order to pay off the previous contributors. The Social Security Administration has the power of the law to force new contributors into its scheme. Maddoff did not have the power of the law to force new contributors into his scheme, therefore, he has been accused of breaking the law. Just another example of it's good to be the king.