People should read some of the background, including haggling over the cost of a murder for hire. - http://www.wired.com/2015/05/silk-road-2/
Truth is, it's hard to run this sort of thing without getting ripped off, and then violence is the only way to discourage people from ripping you off. Watch Godfather movies, esp. part 2... Mafias arise out of human nature and the nature of the game.
One of the many ironies of libertarian extremists is that actions which are considered illegitimate when taken by a democratic government become OK when taken by concentrated private power to protect private property.