I don't smoke pot, but TONS of upper-middle class people do. TONS of people that vote as well. (at least in Austin (and San Jose), they do. :D )
I work with a bunch of people (I'd say out team is about 75 people or so) who make 85-200k a year - I would say that there are maybe 5-6 who DON'T smoke pot on at least a once-in-a-while basis. More than 75% are weekly (or daily wake-n-bake) guys. If an outside polling team asked everyone at work I would bet we would get a 30%-ish return, or less. Stats like the ones posted are woefully inaccurate and certainly have no credibility to anyone with a brain and the ability to reason.
Legalizing marijuana is a freaking no-brainer. Taxing the ever loving fudge out of it makes the fiscal side of me tingle -- lower property taxes, hotel taxes, etc ... yes please. More power back into the hands of local farmers? check. We could go on and on and I don't smoke.