Yes, drugs can be bought with Bitcoin, as can life-saving medical procedures. You see, this digital currency is just that, a currency, like US Dollars, Nigerian Naira, Thai Baht and Russian Ruble, all which are equally adept at buying drugs.
I don't necessarily agree with Bill Gates' comments, but if we were to say that Bitcoin is better and more convenient than fiat, aren't we basically conceding that Bitcoin is more convenient to buy drugs with? That was kind of the point that he was getting at -- it makes it easier for people to buy drugs. It's a weak argument for blaming Bitcoin for deaths for sure, but you can't compare Bitcoin and fiat as equals in this case and say it's better for everything else in the next.
But yeah, I don't think this argument on Bitcoin vs Cash on crime is going to end anytime soon. It's kind of like the argument about guns; those who are against banning it say that criminals are going to use other weapons anyway, while those who are for banning it will say it's easier to kill more people with it than other weapons. Bitcoin can make crime easier thanks to its pseudonymous and decentralized nature, but even if it didn't exist, criminals are going to find other means.
