And the alternative ways to make money for a self respecting criminal are getting harder every day. Cars are more difficult to steal, people use a lot less cash, you have CCTVs everywhere, now the police even collects DNA for a robbery. I can't think of an obvious substitute to drug trafficking for these criminals. I would be also ready to bet that Tinder must have made a dent in the prostitution trade!
But not all drug traffickers are Tony Montanas, there are legions of petty criminals, or even workers who make money on the side dealing drugs.