Yes, nowadays its being used in crime, they buy and sell online and pay by bitcoin. Because its untraceable. So police cant get clue to caught them. I think its dangerous.
You got a valid point on this. Bitcoin is being used for illegal transaction online as well because of its untraceable nature. Though we know that bitcoin is helping a lot of people for an easier transaction for good use, there are also bad people who use it for their own gain to make bad intention for others. Example, the new crime we know now at the internet like the child exploitation live videos allowing the perpetrators to command children to do something illegal. They usually transact through bitcoin to make sure that their transactions has no record to the public.