The kids you know have other things to worry about than weed. They are obviously not mature enough to smoke weed. During the past few months, I have experimented with weed quite a bit, smoking almost daily. It has had no bearing on my academic performance, and, granted it's not the easiest thing to stop doing because you miss the feeling of being high, but it's 100% neither physically, or mentally addictive. I smoke weed because it changes my perception of the world, and allows me to achieve a different level of creativity, and infuse emotion into that creativity. If you think this sounds "pitiful", put it into context. Without question, you yourself have done something, in order to enhance your performance in some area. Whether it be drinking alcohol to take the edge off of starting conversations, or even putting on acne creme, for clearer skin. It's understandable that you would dislike marijuana because it makes people you know become hopeless apathetic addicts, but that's not the weed, that is these kid's personalities
"America is all about speed. Hot, Nasty, Badass speed."
-Elanor Roosevelt, 1936