Earlier quoted context omitted.
Drugs are illegal almost everywhere in the world and they are one of the largest consumer markets. Something similar happens to US dollars in Venezuela. So I don't know if making bitcoin illegal will really hurt its value in the long run.
Your conclusion doesn't follow your observation. It's one thing to say that the government can't stop something, and quite another to say the government can't hurt it. Who knows how much bigger the drug trade would be without anti-drug laws.
Look at the legitimate drug companies for comparison.