Without the WOD, I'm saying that we would have a 50% increase (at a minimum) in the number of users. That's 10 million additional people on drugs. Keeping them off drugs represents a savings in overall economic productivity, savings in medical expenses, savings in insurance costs (for everyone), less drug-associated crime and those costs, etc.
Even if recreational drug use increased 50%, which I think your assumption is wrong, the following is put forth as if it did.
Drug related crime is for the vast majority of the time a result of drug-prohibition. Many people would be more productive if they didn't do hard drugs. Marijuana use out paces other illicit drugs -- save for alcohol which is far more harmful than marijuana -- by are large margin. It's the illicit drug of choice. At a $100 a gram for cocaine and $300 an ounce for marijuana being ten to twenty times the price if they were legal, the cost savings you claim are more than off set. $270 an ounce is going to a drug dealer instead of into the stock market or other place where it could be compounding. People that work hard for their money are more responsible -- more productive -- with their money than drug dealers with their easy 1000% profits.
That said, each person's life is theirs to live as they see fit. Their productivity is first and foremost for their benefit -- not the benefit of society. Communism is the opposite.
People imprisoned add zero productivity to the economy and certainly do not benefit themselves because they do not participate in a free market. No cash flows through them. Lawyer fees to pay for criminal trials of non-violent offenses enrich lawyers, and fees and fines enrich the courts and government. Neither of which pass cash into the economy anywhere even remotely close to the efficiency individuals do. It's mostly consumed by government for government.
BTW, I disagree with your assumption that if drug prohibition was ended along with the WOD that recreational drug use would increase by 50%. I'd be surprised if it increased even 10%. - -
Law Enforcement Against Prohibition -- LEAP. Their member ship is strictly persons that are or have careers in the justice system and fought the war on drugs. Judges, prosecutors, LEOS, DEA, etc.
In 1979, drug use was almost triple its lowest point in the 90's. Returning to the 1979 level would be a 200% increase -- and drugs were illegal in 1979!
Imagine the increase if drugs were legal! My 50% is quite conservative.
You're excluding the possibility that the drug dealer is investing that $270? As far as you know, the drug dealer may be investing in the stock market. So it's a wash.
"People imprisoned add zero productivity to the economy"
That is true. But most of those in prison are there for drug dealing or drug trafficking. If drugs were legal, I don't see them getting a real job. In my opinion, they'd simply switch to smuggling guns or people or cigarettes, or whatever, and end up back in prison for that.
So that's also a wash.