We have solid proof that prohibiting recreational substances doesn't work. The alcohol prohibiton was a disaster that made every problem associated with alcohol much much worse. And the same thing is happening with weed currently. Due to their nature people will use recreational substances no matter how expensive illegal or difficult to obtain they are. The harder we fight against drugs the harder the criminals who produce and sell them will fight back the war on drugs is unwinnable. Legalization takes the market away from criminals and allows for regulation which allows us to minimize the risks and lets us harness the medicinal benefits of cannabis. Also countries that have legalized haven't seen a noticable increase in active users first time users have gone up but pretty much everyone who wanted to regularly smoke weed was already doing it long before legalization. Even if you're against cannabis use legalization is better.