yes when bitcoin was first launched it spreaded like a virus into the whole underworld where it has the complete place for all type of illigal activities and more but thats not truly our point. tor nretwork has many sites running and most ofvthem accepts bitcoin as payment
I think we shout admit the fact that bitcoin is mostly use for good purposes, and may be a little number of bad people using it for illegal activities just like other fiat currency, I think we should always look to the good aspect of everything.
I think we do not need to think about other people's negativ. moreover bitcoin transactions are anonymous and no one knows about the destination on your bitcoin transactions, so it is illegal or not, it does not matter