Koncerned you are posing strawman arguments as you know that no such data is yet available.  Furthermore, you know that the revenue thus far is highly unlikely to outweigh the costs, due to the factors I explained above.  Harping on this question is a red herring.  Let me ask you a question: does it cost more to pursue, arrest, prosecute, and penalize pot-smokers and pot-dealers than the economic activity it produces locally?
Follow-up: is there any demonstrable economic damage that smoking and dealing pot does to a community other than the associated criminal behavior with any black market?