You are assuming that there are advantages to it being illegal. There are not. Legality hasn’t been shown to increase consumption, necessarily. I assume that’s your major false assumption. Next, it’s clearly demonstrable that prohibition creates a variety of massive harmful effects, whereas treating it like a normal business with regulation and taxation has benefits for society.

If you think the government is going to prevent people from smoking cannabis it making it illegal, that policy has been clearly disproven by 40 years of failure. It’s ludicrous to dispute, but some vested interests and clueless people still try, I suppose.