The profitability being high it promotes bad engineering "who cares how much it costs, who cares about the electric bill, you can buy a thousand heads of organic lettuce with profits after selling the weed". Then people try to grow lettuce directly instead of using weed as an intermediary and its not nearly as successful therefore the whole idea must suck or something. Although with better engineering, perhaps indoor lettuce growing could be technically and economically successful if the entire marketplace of weed wasn't stacked up against it.

Sort of a bad money pushes out good money scenario. If it weren't for profitable indoor weed farmers, you'd have higher technology level indoor successful lettuce farmers, and eating is more important to the world than getting high.

Its a scalability argument... when used restaurant fryer oil is free, turning it into free biodiesel is a win, until restaurants start selling used oil and making exclusive deals until its cheaper for everyone to burn diesel instead of making biodiesel, at which point the schemes collapse and used oil again becomes worthless trash. You can feed "A" hippie by selling indoor grown weed and buying produce at the store but you can't feed a planet by having everyone grow indoor weed and buy produce (from who?) at the store. Eventually everyone into weed is going to grow their own and the market will collapse until no one can grow indoor weed and the cycle might repeat.