Their profits are down and the farmers aren't planting it anymore. Also, the DEA is unhappy that cartel profits are down. Makes it seem as if we don't really need them. Aww...it breaks your heart.
https://news.vice.com/article/legal-pot-in-the-us-is-crippling-mexican-cartels
https://news.vice.com/article/legal-pot-in-the-us-is-crippling-mexican-cartels