i think using of bitcoin is depend on negative and positive people if someone is negative then they will use bitcoin for negative activity and if someone positive then they will use bitcoin for the positive activity so we can not blame the the bitcoin because bitcoin is normal currency.
Yes if people activity that is involved with bitcoin is illegal then bitcoin will be used in illegal activities. And when people who use bitcoin are in legal actions, these people will avoid using it in illegal activities because they don't want to be sanctioned by the government. As we know Bitcoin as a currency, it can and will be used at medium to conduct people activity, whether it is legal or illegal