Chances are yes. It is a pretty good bet.
And where the Libertarian argument falls apart — because, by practicing their right to do drugs, we all end up paying for their “right” in the form of welfare. So, no they are not “just harming themselves” but are a burden to the rest of us.
even if there is a correlation, how do we know it's not the welfare that causes the drug use - or that both being on welfare and using drugs are caused by a third factor such as a poor attitude toward life? [...] the question here is whether after legalization we'd be picking up the tab for many more of those exercising their rights to smoke - and the answer is that there's no evidence that we would. Chances are yes. It is a pretty good bet.
I have logic, you have unsupported claims. I'll just let the readers decide.