Pot makes them stupid because they keep smoking all the time!
Edit:
I wouldn't doubt that it does some damage, but in order to do some damage you'd have to be smoking excessively for a long period of time. Used in moderation though, pot won't really change your brain. I know people who smoked frequently starting as early as 7th grade....they all got over 1500 on their SAT's...hm...it is interesting though...i do know of some people who ended up the opposite way. maybe it depends somewhat on the person?
