Sounds fishy to me. Evidence?
The price of illegally sold marijuana here has dropped by 2/3rds since marijuana was legalized. This shows that price is a major consideration of users and the cartels have aggressively sought to maintain market share. Since marijuana is cheap to produce they maintain their profits be selling more.
The property next to my parents 40 acres has been planted with marijuana so many times in the past that it now comes back frequently as an unwanted weed. My dad has to spray it to keep his cows from eating it and getting sick.