Even if society miraculously eliminated its problems, some people would still be attracted to drugs.
Current drug laws are structured in such a way as to leave law enforcement permanently behind and struggling to catch up.
Then again, there was a time when heroin addiction was primarily an urban phenomenon, and that didn’t last.
As far as funds for prevention and treatment, we can look to our experience with problem gambling. Most states where gaming is legal have turned out to be pretty stingy.