This is the correct answer. The underlying mechanism that controls this are the properties of our brain that control habituation. Once the brain has been habituated to a chemical it has been permanently rewired to prefer that state of existence because our bodies are ALWAYS fighting to conserve energy and will ALWAYS resist new rewiring efforts. If it took 10 years of drinking to habituate (rewire) your brain into alcohol consumption it is going to take AT LEAST twice as long to rewire the brain out of the habit permanently. And, that is IF you are even aware of what habituation means and how hard you have to work to rebuild the neural networks through and around the damaged areas. When people say don't do drugs, they don't mean don't do drug. What they mean is that once you are on that path permanently rewiring your brain, eventually you get to a point where there is no undoing the damage and you are going to have to grow new neural wiring around and through the damage. This is why any drinker will be making the decision to stop every day for the rest of their life. Because the re-wired part of their brain will want to get off the wagon every single day.