It's not nearly as addicitive as it's been made out to be, and the chemical addiction only lasts a few days. A number of the other chemicals and toxins in cigarettes pile on top with additional addictions, so when someone tries to quit smoking they're fighting multiple battles. After the short chemical addition there is a psychological addiction though too because it is actually somewhat beneficial to your mind and you'll miss those benefits. It's used to help treat schitzophrenia and bi-polar disorders since it helps the person calm down, be more alert, and it helps with memory. Just do a search for "bi-polar nicotine" and you'll find a lot of sources of info.