there are lots of crimes will happen in this world it will not being supported by cryptocurrency at anytime and people will always use cryptocurrency for good use only and the crimes are always happen for normal paper money I strongly believe cryptocurrency has good way of development.
I think there is a dark side of the cryptocurrency as well but this is true for almost everything around. Look at Elizabeth Holms. She founded Theranos and was something that made her a billionaire but then there have been allegations against her and she had to appear in front of courts. So it is all a game of mind. If you use it for the good, it is a blessing. If not, its a curse.
There is only dark side in crypto currency because the people that make it dark to some other people have a bad intention. Take for example, money laundering, drug dealers, funding terrorists activities, etc are all the activities that people with dark mind make use of crypto currency and make crypto currency look as if is purely meant for dark business.
Firstly, everything that have an advantage must have disadvantage but I wont say the dark side of gambling was prostitution, drugs etc. Besides, I wont say that the dark side of crypto currency was money laundering etc either because the people that abuse the potential of the system the one with dark intentions.