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?
At least a bit of regulation is needed for cryptocurrencies, otherwise they will become a way of creating chaos in civilized world.
Of course, fiats are also used for terrorism and all the shady business, but these can be tracked and prevented in time.
I am really scared when I think of a terrorist attack being done in my own city using the funds related to bitcoin - if this once is being revealed, all my trust in crypto will be vanished.