The question is this, if you legalize drugs, does that mean use will skyrocket? Doubtful. Those attracted and using will still be attracted and using. Those who think taking drugs is stupid will continue to think it is stupid. What will change is the cost to society that was used to house these "criminals" and that those who became wealthy in the blackmarket will lose what was once a lucrative source of income.
Of course it will. Otherwise you are positing that laws have no effect on behavior, which is patently false.
The only realistic solution is to give addicts the best state of the art treatment there is. And if they are found abusing again, you give them summary execution. Drug dealers get summary execution right off.
This worked fine for the Chinese, who were nearly destroyed by opium.