There was one sentence in Sean Penn's weird interview with Joaquín "El Chapo" Guzmán, the head of the huge Sinaloa drug cartel in Mexico, that explains the big problem with the war on drugs: When asked about whether he's responsible for the drug addiction in the world, Guzmán responds, "No, that is false, because the day I don't exist, it's not going to decrease in any way at all."

This week, Mexican officials extradited Guzmán, who was previously recaptured after escaping from prison twice, to the US. The capture was celebrated around the world, including by the Drug Enforcement Administration in the US — and the extradition is seen as a sign that Guzmán will have a much harder time escaping justice this time around.

But for all the celebration, chances are Guzmán's capture, like the captures and deaths of so many drug lords before him, will do nothing to stop the flow of drugs into the US. And even Guzmán knows it.

This is not to suggest that the capture of El Chapo, a mass murderer whose drug cartel has killed thousands of people, is a bad thing. But in terms of winning the war on drugs, it's ultimately inconsequential, even by the federal government's admission. (This is before getting into his semi-retirement by 2014 and the Sinaloa Cartel's unique structure, which Dara Lind and Amanda Taub previously explained for Vox.)

In late 2011, the US Department of Homeland Security issued a memo stating this outright, concluding that "there is no perceptible pattern that correlates either a decrease or increase in drug seizures due to the removal of key [drug trafficking organization] personnel."

This is something even federal law enforcement officials have acknowledged in interviews with the media. In a piece looking at how US and Mexican authorities took down the Tijuana Cartel in the 1990s and 2000s, David Epstein reported for ProPublica that the officials involved in the investigation had a lot of doubts about their ultimate impact:

Herrod is 50 years old now and nearing the end of his career with the DEA. In the time he spent hunting the Arellanos, his hair and goatee went from black to salt-and-pepper to finally just plain salt. He’s proud of the audacity and perseverance it took to bring down the cartel, and he knows he helped prevent murders and kidnappings. But when he looks back, he doesn't see the clear-cut triumph portrayed in press releases. Instead, he and other agents who worked the case say the experience left them disillusioned. And far from stopping the flow of drugs, taking out the [Tijuana Cartel] only cleared territory for Joaquín Guzmán Loera — aka "El Chapo" — and his now nearly unstoppable Sinaloa cartel. Guzmán even lent the DEA a hand.

So the capture of El Chapo, and whatever damage it does to the Sinaloa Cartel, will likely continue a cycle long known in the war on drugs.

The drug trade is too profitable to go away

How is it possible that defeating a drug lord or cartel doesn't stop the flow of drugs? The problem is what's known as the "hydra effect": When one source of drugs shuts down, another takes its place. The name comes from the mythological hydra, a beast that, in some versions of the story, grew another head when its previous one was cut off.

Since drugs are so lucrative, drug producers and traffickers don't just cease to exist when governments detain or kill them. The business is so profitable that someone will always be there, willing to replace defunct organizations or leaders. In this case, the fall of El Chapo won't lead to the end of the drug trade, but instead will lead to someone else replacing him as head of the Sinaloa Cartel. And even if the Sinaloa Cartel collapsed — a very unlikely event — another drug trafficking organization would take its place.

The effect is similar to the "balloon effect," when cracking down on the drug trade in one area simply moves it to another area — sort of like pushing down on a balloon can simply move the air to other parts of the balloon. This effect has been documented all around the world, including Colombia, Mexico, Venezuela, Ecuador, and West Africa.

Since drugs are so lucrative, drug producers and traffickers don't just cease to exist when governments detain or kill them

The general point is that taking out heads of cartels or the cartels themselves won't rid the world of drugs, but will instead shift the drug trade to other criminals.

These effects are an expected result of the war on drugs — in what's known as the "profit paradox." One of the primary goals of the drug war is to make drugs more expensive by limiting their supply — the idea being that a drug habit is much more difficult to sustain if drugs are more expensive. But this also makes drugs immensely profitable: According to Jon Caulkins, a drug policy expert at Carnegie Mellon University, the war on drugs increases the price of drugs from production to sale in the US by as much as 10 times. This creates a paradox in which drugs are less accessible but the drugs that are sold are enormously profitable for criminal organizations, despite all the troubles of smuggling the substances through Latin America and into the US.

What's worse, capturing or killing the heads of drug cartels can actually lead to more violence. By leaving a power vacuum in place, and because drugs are so profitable that a top spot in the drug trade is always desired, the end of a drug lord's reign often leads to a battle between aspiring successors.

As former DEA head Michelle Leonhart once said of Mexico's violence, "It may seem contradictory, but the unfortunate level of violence is a sign of success in the fight against drugs."

Indeed, there are already reports that the power vacuum left by the weakened Sinaloa Cartel has led to increased violence across Mexico.

Again, that's not to say that the capture of El Chapo was all bad. He was a mass murderer, and it's important that the justice system, whether in the US or Mexico, shows these types of criminals that they can't get away with their horrific crimes. But all signs suggest that he will simply be replaced — and the drug war will continue consuming lives around the world.