Would more people be addicts if drugs were legalized? Sure. But as a result of legalization, drug prices would go down, so you'd have LESS theft, burglaries, robberies, etc. by people trying to fund their habit.
And, TBH, I don't think that drug usage would EXPLODE... Many people still want jobs and have life goals, they will not become addicts. Myself, I've tried heroin, speed, and other highly addictive drugs (mainly opiates) and have never became addicted. For me, addiction isn't worth it, and I think many people are of the same mind. BTW, when all drugs were legal in the early 1900s, about 1% of the American public was addicted to some kind of drug - that's not very much. Moreover, some of these drug addictions can coexist with a somewhat normal life - for example, heroin addiction used to be popular among middle class white women who were by almost all definitions "respectable." It's really the drug war that has fueled the thievery, the despicable behavior, etc. More recently, coke used to be popular with many successful investors on Wall Street. In fact, I know a successful investor who smokes weed every day and snorts coke somewhat regularly (not every day, but on a weekly basis). There are a lot of completely moral and legal things that people can do in order to fund their addiction.
There are other benefits that would come with legalization:
- No more exploding meth labs in neighborhoods.
- Drugs would come in standard doses, thereby greatly cutting down on overdose.
- Drugs would not be contaminated with other chemicals, thereby cutting down on other health issues.
- Significantly reduced gang violence and no more full-scale wars between drug cartels.
- Drug addicts would be more willing to seek help from the medical community, etc. since they'd no longer fear being legally punished.