I don't consume any drug but alcohol (socially). However, I have knowledge that buyers can buy any kind of drug trustfully and anonymously thanks to bitcoin (whether in legal or illegal markets).
IMHO, this isn't bad for bitcoin, nor for the world. Bitcoin give true liberty to the people. I also think we should better help people with drug abuse problems rather than ban drugs.
may be no one can know about the fact that either bitcoin is really using for illegal activities like for buying drugs or not because bitcoin is a anonymous currency and no one can no about the activities for which bitcoin is being used.
You do not need to worry over that, because it is already a lot know that the greatest strength of the growth of the bitcoin is an illegal activity carried out by those who are just looking for the profits for themselves and the group. But it all was not the beginning of the destruction of the bitcoin for bitcoin will still exist and will grow more in the virtual world. Everything will definitely switch to using bitcoin system because they do are very profitable