Is smoking pot Harmful? Well...
A few months ago a Mexican friend of mine invited me to his birthday where I proceeded to get drunk on beer and threw up. I've never been that drunk before, and I hope never again. I'm not an alcoholic. I can live without alcohol but enjoy it on occasion. For me getting too drunk is not enjoyable.
Around that same time I took up smoking pipe tobacco. Normally, one is not supposed to inhale, but I did on occasion. While I got the nicotine buzz, I didn't get addicted to it. I have since stopped smoking and kept the pipe as a souvenir.
About the same time that I tried tobacco, another Hispanic friend of mine got me some "mota," i.e. pot. I finally got to feel really stoned for the first time in my life. I must say that things taste better when I'm stoned, and some of the other sensations are rather novel as well. After about a week of smoking pot in my off hours, I had had about enough of it. I just didn't want any more.
Was it harmful? In a physical sense it was probably no more harmful than the industrial chemicals I have repeatedly been required to work with in my places of employment, the cummulative effect of which has caused me a certain amount of respiratory and nerve damage. It is probably no more physically harmful than a lifetime of eating meat, dairy, soft drinks, and refined foods, which have led to circulatory system damage and intestinal problems.
The only difference is that pot is not a socially acceptable way of harming one's health, assuming it is smoked, while many other substances which we ingest or inhale still are. When compared to tobacco and alcohol, well with tobacco the buzz seems rather pointless, so I smoked it for its taste. Both alcohol and pot make one intoxicated. I can't understand why the intoxicating effect of alcohol is considered legally acceptable for recreational settings while the intoxicating effect of pot is not. Being drunk can't be any healthier than being stoned, and long term alcohol use can have severe health consequences.
Pot is illegal because the legal system generates revenue by keeping it that way.