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?
Yes indeed, it is very important to regulate crypto currency inside the internet where lots of people lives. Since majority of all the people in the world are capable of accessing the internet. It is very risky for everyone to commit the money.
However, I don't think that Bitcoin and digital currency will be regulated as a whole because internet is a wide field of possibilities. Thus, it is only possible for a certain country to be regulated if the government does.