I'm only referring to high school because that's what almost everyone on this form is. You seem to be missing my point. I'm not saying you become less intelligent, I'm saying that the people who do drugs aren't going to be your most intelligent people. Smart people don't normally do stupid things. The people who have above average grades and are at the top of the class aren't going to want to ruin all their work because they have "possession of marijuana" on their record.
And sorry if I offend you, but face it, most people who do pot probably don't have much of a life. That's why they resort to doing pot, instead of doing something like working out that still gives you a good feeling.
Studies, like the one I posted, show that people who try pot are generally similar people. Just like most of the people who play Blockland are people who played with LEGOs as kids.