There is always an entity to sue, because legal and organized business activity is taxed and requires legal entities. If you hide your commercial activity from

There is always an entity to sue, because legal and organized business activity is taxed and requires legal entities. If you hide your commercial activity from taxation, you will be dealing with law enforcement sooner or later, depending on scale. For example, I can sue all companies that make operation of Bitcoin possible, including exchanges, miners, individual and organized Bitcoin users. So, to repeat: Technical implementation details are irrelevant because legal business happens between legal entities.