Many people hate cannabis because it makes them sleepy or unable to complete daily tasks, plenty of people take speed related drugs to have more energy. Does that suddenly make speed ok and weed not?. This is what I am saying, you are not dealing in logic.
Your argument of giving people free choice is flawed because it is dismissive of the deterrent law has on the amount of said action, be it rape, murder, drug use, weapons, fraud.. anything. You very naively assume the typical person is responsible or has a good moral compass. The only reason you have any human rights, the reason a person does not smash your head in with the nearest object when you annoy them, is because of law. Law is so effective that for the most part, it is only a person with mental issues who is going to take away your humans rights. Most reasonable people weight up the odds and realise a huge fine or time/life in jail isn't worth it.
Cannabis is not as bad as the things above. Read that again.. because I keep saying it. However it does have downsides that should be taken serious. It should not be completely legal for anybody to smoke, due to the increase in general population availability and increased consumption > side effects that would follow. On a medical prescription basis (same as heavy pain killers) particularly cannabis oils, yes, 100% legalise it for that. As I said, they are suffering enough that the downsides of cannabis are compensated by the upsides. A normal healthy person heavily smoking cannabis is only getting one subjective upside, enjoyment of being high. That isn't worth the downsides that come with it.