If you use a "hard drug" and become addicted to it and can afford your habit, that's your problem.
No. I totally agree, but how often does that happen?
Having something in your pocket that other people disapprove of is not a crime and has no victim.
I see your point, but my point is that there are so many ifs and buts that the discussion about "consenting adults" is mainly a theoretical discussion. Reality is different. In daily life people are just not free to do what they want. In general, yes, but not as a rule. Take gay marriage between two consenting adults.
Most drug users are not able to support their need by them selves and cause many problems for society. Or to put it, they're not able to behave along the line of consenting adults so no freedom of drug use.
Apart from that, the war on drugs is a waste of money. Is that money was spent on prevention, drugs related crime and taking care (basic shelter, clean needles, some medical care) of the drug user. there would probably even be a lot of money left for these people: http://www.infowars.com/101m-americans-get-food-aid-from-federal-govt/