Aside from the very real conspiracy theories presented above, I think there's another reason lurking just below the surface...one that not every pot smoker wants to acknowledge. The most vocal and outspoken (and therefore most noticed) pro-pot "activists" tend to fall into the hippie/rasta/burnout stereotype categories. They never have and never will be taken seriously...they represent to middle America failure and something they fear their children growing up to become (right or wrong).  I think we all have met or maybe even are one of those high functioning (pun intended) pot smokers. But hey, the CEO of my small town bank isn't going to band together with the city council president and push for legalization. These guys have the best of both worlds...they have a better than average income and likely have a solid dealer who is way under the radar of local law enforcement (or supplies them too) and they get to enjoy their little one hitters in the privacy of their home with little to no risk of getting caught.  On top of that, their semi-secret habit makes their dull, middle aged, 9-5 life a little more exciting by adding that "outlaw" aspect of smoking. Let's face it...isn't that small risk of getting caught half the enjoyment?

I don't support legalization of marijuana and yes I do smoke myself (occasionally), but it would disrupt working habits and other vital roles of life. Could you imagine if I told my boss 

If the USA would pull their heads out of their asses and legalize weed California might actually get out of the red, they would save billions on no longer enforcing such a pathetic thing, and they would make a killing off the taxation.

It should be set up like Beer more than Cig's though, follow the Dutch concept with Coffee Shops. The whole argument of people being too stoned to work is a pretty weak one in general, you will have a certain amount of the population like that, but my guess is more will just be rec users and not outright stoners.