Did you notice that only the people who do not smoke Marijuana think that it is addictive? Believe me, it is not. It knows when to stop. Or your body knows, when it's had enough. I've been smoking Marijuana for two years, and I can say from my one experience - there are times, when I smoke every night, for maybe two or three weeks, and then there are months when I don't do it at all, simply because I don't feel like. No addiction is formed. As for getting paranoid - well, I never experienced this, but people might have different reactions. I only get positive feelings and useful ideas. For me, Marijuana is something that helps to make an unbiased analysis of some situation.
Alcohol is a far more dangerous substance. Those, who think that alcohol is not addictive, should take a field trip to some special clinic and take a good look at all those alcoholics. Alcohol is very, very addictive. And its main danger lies in the fact that people take few precautions with it. I mean, if you are about to take some substance, like Marijuana, or to take some drug for the first time, you realise that you are doing what few people do, so it makes you more careful. And alcohol is a kind of a social habit (and a very bad one, IMO). Everyone takes it, so what's the problem? So it is much easier to become addicted to alcohol, as it is also more available.
Marijuana helps to open doors in your mind that would otherwise remain closed forever. I think that this is the main reason why it is illegal. Alcohol doesn't do anything of the kind - it just stupefies you and makes you mess up your life and all the situations you might be in when drinking.
And, by the way, look at the Netherlands - Marijuana is legal there, and the Netherlands, nevertheless, is not a country of paranoics