Boom and bust. I think the same thing happened in Washington or Oregon. The pot shops kept having to lower their prices until they were crying they weren't making any money. I believe the illegal Chinese pot farms were a big part of the reason too.
See the cartoon at the link for all the damage NM “progressive” libs have done to the state:
https://freerepublic.com/focus/f-news/4197607/reply?c=1
Since the cartoon you can add restrictive gun legislation to things that drive New Mexicans to Texas.