https://www.deepdotweb.com/2016/01/23/bitcoin-playing-an-increased-role-in-crime-europol-says/Would you believe that the existence of bitcoin has increased the number of criminality in some countries in the world. This is the issue that was being thrown by the EuroPol and the UK Metropolitan Police. According to them bitcoin has played a huge role on the increasing criminality in their area. They added that a huge number of cybercriminals were using bitcoins in their activities.
This just shows that as bitcoin develops both advantages and disadvantages will tag along.
I think there are very few criminal incidents related to bitcoin. Bitcoin, as an encrypted currency, is anonymous and decentralized, and the government cannot control it, which is why it is used as a currency of exchange. But I don't think that's why bitcoin is banned.