Not necessarily, I suspect. All the people who want to use drugs are using them now. What legalization might do is reduce the push for newer members of the club. If legalization took the profit out of it, would the current pushers still be pushing?
Come live in an older neighborhood now where there are a lot of drug users, the only thing keeping it partly under control is fear of getting caught. The two kids who drove into my house didn't care about hitting my house or that they could have killed me, they only worried about hiding their drugs before the police arrived. Once there is no incentive to prevent them frm doing it they will do it more often and you will see a lot more accidents from it.