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?
In my own opinion, we really don't need to regulate crypto currencies but regulations can be also helpful with the adoption and growth of them or they can be restrictive and even prevent the adoption altogether. In the end it will come down to what will they regulate and how will they regulate bitcoin or crypto currency. For example, if it is regulation of exchanges and if it leads to a more secure place where people can trade with less risk that would be a very good thing but if the regulation of bitcoin will affect the value of bitcoin and other crypto currency then maybe we should not let bitcoin to be regulated.