MedMen was the country’s hottest pot startup—until it flamed out. Its fall has exposed the gap between “green rush” hype and the realities of a troubled industry.

The warm California sun shone down on Adam Bierman as he stepped up to the ceremonial ribbon strung across the entrance of his latest triumph: a new store on Abbot Kinney Boulevard in Venice, the hottest retail strip west of the Mississippi.

Bierman stood facing a pack of clamoring photographers...

MedMen was the country’s hottest pot startup—until it flamed out. Its fall has exposed the gap between “green rush” hype and the realities of a troubled industry.

The warm California sun shone down on Adam Bierman as he stepped up to the ceremonial ribbon strung across the entrance of his latest triumph: a new store on Abbot Kinney Boulevard in Venice, the hottest retail strip west of the Mississippi.

Bierman stood facing a pack of clamoring photographers...