You really want think creating a drug based startup is a good idea? Who would buy it? No one would advertise on it. No users would pay for it. And it would be morally questionable. But if that's what floats your boat...
Yes I think starting a cannabis related startup is a good idea. I live in Colorado where we have over 100,000 medicinal patients and a dispensary on every other street in the Denver area. Combine that with a staggering amount of people that consume cannabis recreationally, unaffiliated with the medicinal program, and you can see how there's a pretty enormous market in this state alone. Now take into consideration the relative size of California and the fact that every single one of its citizens of legal age could potentially be buyers of this product.
Nobody would advertise on it? The Denver Post disagrees with you mightily ---> http://www.denverpost.com/news/marijuana ... oh yeah, the Westword Magazine disagrees with you too ---> http://www.westword.com/directory/marijuana-dispensaries/
Do you have any idea the amount of shops that are going to be offering cannabis products? You don't think, I don't know, that THOSE people would like to advertise? Or the glass blowers that make a living making pipes, bowls, etc? Or the vaporizer manufacturers like http://silversurfervap.com or the web developers that make most of their money designing sites for dispensaries in medicinal states? What about grow light suppliers like http://www.sunlightsupply.com or the nutrient companies like http://www.generalhydroponics.com/ or the full hydro/grow stores like http://www.thebigtomato.com/ ?? Consider the seed banks like http://www.cannabis-seeds-bank.co.uk/ that will be bringing their business to California. Think of the apparel companies that sell cannabis related gear. Think of the music industry when it finally adopts weed in out in the open. Think of the electricians that specialize in wiring grow rooms from small all the way up to the warehouse sized ones that dispensaries run around here.
Edit: You know what, I'm not even done. Here are some more people that "wouldn't advertise" -- cannabis edible makers and drink makers like http://www.keefcola.com/ , online communities like http://www.icmag.com , cannabis breeders like DJ Short, companies that sell point of sale software to dispensaries, credit card processors, etc etc etc.
This is so much bigger than you'll ever know, and it makes me sad that you have such a negative attitude towards it. This is bigger than the gold rush and bigger than silicon valley.
And we're only talking about California. Think of when the next state adopts it. And the next. And the next.
I also find it ironic that you think nobody would "buy" a cannabis related startup when this very thread is about a very wealthy individual investing $100,000 already, and the law hasn't even passed yet. Imagine the projects he's got his eyes on for when it actually DOES pass.
Mark my words, if legalization takes hold you're going to see your first cannabis entrepreneur break the Forbes 400 in a very short amount of time.
I would if it would connect with my target group.