I can brew my own beer relatively easily in the comfort of my own home, for the final price of less than $1 per beer in ingredients. I still buy much more beer at the store than I brew.
The beer industry is a good example. It's nowhere near as powerful or nefarious as Big Tobacco, and in fact the phrase "Big Beer" doesn't doesn't even exist. Beer companies tend to be fairly benign, while the tobacco industry is famous for stunts like marketing cigarettes to kids and trying to suppress anything that suggests their products are harmful or addictive.
So if the marijuana industry turns out like the beer industry, that will be a pretty good outcome, really.
Any public health measures are rigorously campaigned against.
The all-party parliamentary beer group receives funding from the alcohol trade. http://www.publications.parliament.uk/pa/cm/cmallparty/regis...
(What's the largest uk appg?)
[0]: http://www.ab-inbev.com/go/brands/brand_portfolio/local_bran...