Currently bitcoin has been widely used for crimes because their crimes are difficult to trace if transactions use bitcoin.  It just really depends on how the person is using it and that is why police come in and to do investigations for those who commit crimes. The Internet can be also the source of crime but the government doesn't shut down the internet because it can be also their source to find the criminals there are cons and prons but in reality, bitcoin is just another currency which people wants. We should not blame bitcoin for the wrongdoings of the criminals.