Digital currency is to change the world, many of which were positive, to a certain extent, they pose a containment of the government, gave the people an alternative, but that doesn't mean they don't need to be regulated.
One of the core reason is: anonymous, do not track, not regulated digital currency will make form a closed loop technology crime, money laundering and terrorist, and disappear from unsolved bits, bytes, while the impact damage with each person in this world.
If every penny of extortion is tracked, is there enough motivation and courage to launch a WannaCry to attack the world?
I think bitcoin cannot be fully regulated by any government body. But I hope that bitcoin itself at least have its own regulations to stop illegal activities under it. It will be hard to achieve but with the advancement of technology as day passes. May be in the future, bitcoin can ba regulated by its own.