The problem is actually that the media has made it difficult for government agents to arrest people for selling and consuming it. The DEA also blames the increasing trend of legalization across the United States. In its 2016 National Drug Threat Assessment Summary [pdf], the DEA observes that "While marijuana remains illegal under federal law, many states have passed laws allowing the cultivation, possession, and use of marijuana within their respective states."
The agency then argues:
"Due to these varying state laws, as well as an abundance of media attention surrounding claims of possible medical benefits, the general public has been introduced to contradictory and often inaccurate information regarding the legality and benefits of marijuana use."