Why or why not do you think marijuana should be legalized?

I think it would be a bad idea. If you made it legal, people would be going anywhere blazed and stoned. Half of the people in my school, which is a highly ranked high school, blow trees. The people that are baked are practically walking dead. They can have a conversation, but fail to really pay attention or grasp any topics or lessons from classes. And the whole point of school is to learn. Legalizing pot would make it easy to buy, say at the local 7/11. People would be high all the time. How would the passengers feel if their bus driver is high, and how would an employer feel if employees came in to perform tasks high? Why legalize something that is detrimental to your health and there purely to trick your mind into thinking you aren't harming yourself or someone else? I do not consider the argument that it was made by god, or that it is natural, and therefore should not be banned a viable argument. Heroine, meth, crack, cyanide, anthrax, and uranium are all natural. Yet I don't hear too many people arguing that you should be allowed to carry crack or anthrax on your person. I wouldnt want half the population looking like the pot heads at my school. It is specifically considered a 'gateway drug' (now I know that sounds dumb, and I might sound like a person at an antidrug assembly) but it truly is. Who really stops at ganja and doesnt try anything else? The half the population that would be high off pot would also have a quarter of that high off really dangerous things like PCP and wet. I think legalizing marijuana would be a terrible idea. You guys?