Yes, actually. Think about it. The decision to do drugs is a personal choice that does not interfere with anyone else's life. If someone chooses to use, then it's their own choice. Had he been holding people at gunpoint, forcing them to take it, it would be wrong. Something is wrong only if it causes direct harm to another person outside of a personal choice. I.E. Your murder of his bodyguard and him. For some reason, when people hear about a druggie robbing a store or killing someone, they can't separate that from the drug use. His drug use was perfectly fine, his violence towards other was where he went wrong.
Of course, the War on (Some) Drugs has taught people not to question these things too much.