Where to start. Firstly, You wouldnt be growing "cannabis" to meet the "unlimited" needs, you would be growing hemp. Second, your right, people dont grow there own tomatoes always. Because when you grow a tomato plant, you get enough for maybe a month, and they go bad eventually, so you can even save them for very long. Cannabis on the other hand, you grow your own outside and if you pay it any real attention you are going to get enough to last several months, and it can be dried and saved. Most things that can be dried and saved, dont grow most places, cannabis on the other hand can grow pretty much anywhere, with varying levels of quality. Basically, you can produce plenty without a very large amount of work if its legal. You could even put a lot of work into it and produce even more and even better product. Not everyone would do this, but nobody and I mean nobody would ever pay $60 for a bag.
The would not add anything? We already add shit, they are just going to cut costs, and try and make more profit by trying to make it addictive. People smoked tobacco for many, many, many years without anywhere near the same level of issues we have. They put a lot of crap into tobacco. Little known fact: tobacco doesnt just come up with most of those things you hear as horror stories, they have to be there to get into them.
Back to the price and quantity. Look at corn, we could produce a lot more, and make it way cheaper. They force the price up, which doesnt mean it has to be there, it means they are making an active effort to go against potential. People are starving and we have no money. It hurts double paying to make less food. Hemp has even more potential than corn. Unless strict limitations are put in place to force price to remain high, availability and cost of production would make the price be horrible. Instead of trying to make sure its a money maker, make it gov run. Don't make it about profit, make it about keeping the people fed, clothed and the world a better place. Go in the sense of a park. Parks dont make money, they eat it, but they make people happy. They would not just increase supply to make the same proffit because there is a finit buyer base. Just having more product doesnt mean more money. Nobody has money these days to begin with. Making things cheaper would be great, and people could buy more but you have to make sure there is a demand, which would be easy to fill unlimited demand if allowed. As it is, we have this social stimga against it and would need to work on that already. People tote numbers like 40 billion around based on $60/8th. With legalization the price would fall dramatically. Demand wouldnt go up enough to make it back up to the 40 billion. There would obviously be money to be made, but not the wonder numbers people tote. In the end, its not about numbers though its about saving the world. Dropped prices would spread out the wealth more evenly.
The shrink/augmentation ray is here, hemp. It basically is a tree, but grows hundreds of times faster. Who needs to enlarge a loaf of bread 50 times when you can make 50 loafs? Hemp can meet the unlimited demand, but it takes a lot of work. You cant just grow 400 acres of hemp and put up a sign, expecting it to work out. You need to make it into another form. Make it into bread, but that takes time and money. The bread though, because just about anyone can do it would be very cheap. You just cant go into it hoping to make a ton of money. Money is made by limited resources. Hemp is effectively unlimited.
Socialism is the only basis it could truly work. With buisnesses competeing with eachother, nobody would want to do it in the end, unil only one big company remained, or maybe a few, but they would set the price. Hemp cant supply the world with every single thing, but the supplementation, along with the other things it cant would make a lot more people happy. Salt may stay the same, but when the food your using it on is pennies, it doesnt hurt as much.
Basically, your argument is "just because it can, doesnt mean it will", which really isnt arguing against me. My point is kinda that we have the chance to save everyone, but we wont take it because we are lazy pricks. It is there, it doesnt mean we will. The big issue is currently, we cant.
I don't know what is the attitude in your nation, but in our country those people that I have spoken with - four from 5 will say that mj is the shortest way to other drugs. Our society isn't educated enough about pros and cons of mj. This is because objective researches are not shown globally. What are pros and cons of American society? 
