“By seizing drugs, what the police are doing is raising the price of drugs that have not been seized.” ~ Fernando Villegas
By increasing the risk of production, they also increase the price.
The police help the narcos become millionaires.
Discussion
Most police aren't that bright
They do not need to be, it is enough to exist to interfere in the market. Just as during prohibition, mafias were created that shot each other to death for territory, the price of alcohol increased and many people died intoxicated by dangerous chemicals mixed with different types of non-drinking alcohol.
But it is still believed that the war on drugs has been a good policy.