I can't debate in the proving grounds.... only a select few can.
I guarantee you, I have. They did not die due to what the drug did to their body, but because of what it did to their mind. They weren't all there due to the effects of the drug.
My point is you never know until you do it. Some people have "bad highs". My cousin had one such that he had to have myself, and 3 of his friends hold him down because he wanted to kill himself. Also not to mention the crashes when coming off the drug (such as heroine, I happen to know an ex-addict. My best friends aunt, who is currently living with him and his family so they can keep watch over her for a while).
Drugs are far more addictive then over the counter medicines. They also have a far larger amount of people affected negatively then legal drugs. Also again, tell me what cocaine or PCP treats? I know sleeping pills help with insomnia which is a real, and terrible condition. (I should know, I am an insomniac. But I also don't take pills for it, because I don't take pills for anything unless I'd day if I didn't)
Also you can die from everything. You can die in your sleep, you can die from a heart attack, you can die because someone ran a red light, you can die because you were at the wrong place, at the wrong time. You can die because you slipped and fell and hit your head the wrong way. The government can't honestly make everything that can kill you illegal. You'd literally have to not exist. Staying inside your house can kill you, and leaving only increases those chances.
Ok, different comparison this time. I would personally love to not go to school, I see little purpose in it. (I can learn anything I can learn in school, online) however if I don't show up. I'm breaking the law. Is it better for my happiness? Yes. Is it better for society as a whole? Arguably not. Although it is beneficial in some ways.
Also drug users do affect those around them, thinking that they do not means you live in a perfect world. Again, drugs such as cocaine increase aggressive behaviors.
Life, Liberty, and the pursuit of happiness. But if you truly understood why it says such, it is because the government could not promise property. It was a slightly changed point of view from John Locke's own "Life, liberty, and property". Considering we cannot promise land to everyone, we can promise them the pursuit of such land.
It depends how you infer the statement "pursuit of happiness", as there are several arguable and "correct" ways to view it.