Mr Sandman said, "Yes, Cannabis just triggered the metal illness.

As far as I am concerned , it doesn't really matter, the mental illness is exacerbated."
You (perhap's wilfully) misunderstood what I wrote, I was saying that this hypothetical person was already mentally ill or depressed. They one day try cannabis and find it makes them feel different, happier. They then quite rationally want to repeat this experience because it aleviates's their symptom's. Also just because someone takes drug's does not automatically mean their mental state is changed beyond the immediate effects ie long term personality change (of course the evidence suggest's that long term use can cause problem's).
Also he said, "The lesser evil would be not even smoking or doing mind altering drugs".
This statement has merit, but it is your own view or "opinion" it may not be applicable to everyone on this planet namely because each individual has a different set of personal ideas and ideals.
And then, "And for your info, more people would chain smoke weed if it were legal.."
How did you come to this amazing conclusion, what evidence do you have to back it up? Given from the tone of your posting's in this topic you do not and have not taken cannabis so have no personal experience in what smoking it entails or how much it take's to get stoned. Most people I know who smoke or have smoked in the past smoke enough to get high then stop because once there, there is really no point in burning more weed to no discernable effect. Also to make another point look at the prohibition era America, the criminalisation of possesing and using Alcohol did little to reduce consumption it encouraged black marketeering, gansterism and lead to valuable tax dollars and police time on enforcing what essentially was an unenforcable set of laws.
Also, "As I said easier, it doesnt matter. People are weak and do not how to be responsible. So for the safety of all drugs should be illegal."
I strongly resent this you are implying that I don't know how to be responsible and that I'm weak. You Sir are an arrogant, restrictive... I won't continue for fear of getting banned off the forum. But to deconstruct this point, did I read correctly? ALL drugs should be illegal? What about antibiotics, antihistamines, antidepressants and painkillers. Without these advancement's in medicine we would be medically in Medeval times.
And again, "Lets not forget that your mind can kill you. While a mental addiction may be just a craving, a junkie might go though some means of getting such illicit materials to feed his habits thus exposing him or her to situations that can just as easily kill him.
Take the normal garden variety junky. To get his next fix he might steal form people to get money to get it. He might even commit murder for money. Thus, he can be planted in may situations by drug lords, so that he may die, or he may get arrested and go to jail."
Might. Just because a person take's drugs does not mean that their moral fibre get's overwritten by the need to obtain more drugs. Many quite respectable people who smoke cannabis hold down jobs, own a house etc. Drugs aren't to blame for an individual persons actions, everyone makes their own choices.
I am suprised that someone even at 17 could be as naive as you appear to be, please understand I am not trying to be unpleasant by saying that. Just try have a more open outlook on life it would be a pity if your veiws became rigid at such a young age.