If feasibly testable, then yes. If you need the government to help you pay your food/medical/housing/whatever bills, you should not be buying alcohol/cigarettes. Caffeine is debatable, because for many people it's not about recreation, it's more about giving you that extra kick so that you're more productive.
I feel like the best thing to do in regards to drug legalization is to try to empirically link each class/type of drug to various societal outputs, like productivity, price of medical care, etc, and then tax the drugs accordingly.
Meth decrease general productivity by 100%? Tax it at a higher rate. Cocaine/MDMA/LSD have benefits and fewer side affects? Tax them at lower rates.
