I don't really believe that the illegal status of Marijuana has much to do with drug companies or any other kinds of big corporations protecting their profits. I think it has more to do with the fear of many people that legalizing weed would make us all into potheads, and our society would fall apart because no one would ever get anything done. Or maybe they are not worried about society as a whole, but just worried that their own kid would become a pot-smoking drop-out loser, smoking blunts, eating Dorritos, and playing video games in their bedroom and never move out of the house.

Whatever the fear is, many people who have no corporate profits at stake see weed as a detriment to society and do not want to see it legal. So because of that, there are very few politicians who are going to be intereted in spending much of their political capital on fighting the fight for legalizing weed. There's a lot to lose by taking on that battle, and from a politician's point of view, there is not a lot to gain.

Probably the best you can hope for is to have politicians decide that the money they are wasting on the bogus War on Drugs is money they would like to spend elsewhere. All politicians have their own priorities, and maybe if some other prioritiy becomes more important than hunting down people in the pot trade, then maybe something will change.