I see where your'e going. But to use a crass example.

Lots of Fat people have issues not eating, they are addicted to sugar, chocolate, whatever. Which means food is an addictive substance to them. Its often fucking their life up too. They often have massive problems stopping.

So Im not sure thats useful in the debate as a definition 

People are addictive as a rule, what happens to addict them changes.  Not just consumables either.... anything that changes your body chemistry can cause you a psychological addiction.... excercise is often mentioned.

Absolutely right and loads of work is being done to develop work around eating habits and healthy lifestyle as well- certainly in the UK huge amounts of money are going into this field (of course it has to come from somewhere- so other less fashionable issues lose support).

However eating is a neccessary part of life- smoking isn't. It's easier to quit smoking (anything)completely than to give up food completely. Lets face it most addicts only quit by avoiding their "poison" completely

Why those drugs? Personally I've seen more people fucked up from long term cannabis use than "harder" drugs. Just my personal experience admittedly.

I'd argue that all drugs have the potential to damage you, and anyone who dismisses cannabis as not being REALLY dangerous is, in my opinion, an idiot. Question is, do you allow people to freely damage themselves or do you regulate it?

edit - curtailed rant after second reading..

imo its a mistake to justify a legalisation question for one damaging substance based on the status another - its not really a sliding scale of severity. I think I probably err on the side of legalisation because at least that way there would be regulation of dosage, and it could be taxed.

My prior experience of smokers has been (both professionally and socially), that they are usually calmer than other drug users (especially alcohol)and less likely to cause problems for anyone but themselves. Over the last 5 years I've become used to the idea that (younger-i.e under 25 yrs)Cannabis users are likely to be violent (often to extreme), and as this is the age group that society is having a moral panic over, it's their behaviour which will influence policy makers.

It's not even that they're mixing it with booze, many of them don't drink- preferring to smoke, - they chain smoke spliff until they white out, often using huge amounts in a session- almost like a kid with Easter eggs, stuffing their face 'til they're sick.