So you support alcohol prohibition, too? How many gangs are funded via the illicit sale of alcohol today? Gangs need money to survive and recruit new members. Make drugs legal, and their only real source of income disappears.
As I said, during the 1920's I'm sure they said, "Make alcohol legal, and their only real source of income disappears".
I don't believe you. I don't believe the gangs will go away. I don't believe they'll all go out and get a real job.
Make drugs legal and they'll sell any drug not made legal to any age not allowed. Regulate the content and purity, and they'll sell something stronger. Tax it heavily and they'll sell it tax-free.
Legalize drugs and the gangs will get into the export market, selling legal American drugs to countries where it remains illegal. (They already have the pipelines established -- simply reverse the flow.)
We would have to legalize all drugs to all ages, unregulated, tax free, worldwide, to achieve your goal. Then the gangs would shift to smuggling guns, people, diamonds, donor organs, whatever.
What they WON'T do is get a job.