Keep in mind that normal, middle-class people do not get to hire contract killers. You might come into contact with somebody, but what will end up happening is that he will turn informant to the police in exchange for them ignoring some minor legal issues. When you hand over the money, they arrest you, and the contractor keeps your money.
Oh, real contract killers exist -- but they are only hired by people "in the business" who have the ability and willingness to PERSONALLY do unpleasant things to people who cross them, and only hire contractors to establish distance between themselves and the target.
YOU NEVER KNOW who knows who. So why cut off their options to use the civil courts to strip you bare and leave you penniless on the streets. Isn't it better to be poor than to be right and dead?