My dad was a college professor with many published works and certainly a genius level intellect. He smoked cannabis and didn't seem to have a problem. I became disillusioned with education and never pursued it more than I had to but I don't think smoking almost every day has done anything to hinder my thinking. I definitely don't feel dumber than the vast majority of people. I think we all have the potential to be super-geniuses actually and it's very limited to think things like "Weed makes you lost."