Yet trials with never smokers and pure nicotine don't show that as a result:
Nicotine treatment of mild cognitive impairment
15mg /day (equal to 18 cigarettes) for 6 months. No dependence noted
Study finds nicotine safe, helps in Alzheimer's, Parkinson's | Tampa Bay Times
"It seems very safe even in nonsmokers," he said. "In our studies we find it actually reduces blood pressure chronically. And there were no addiction or withdrawal problems, and nobody started smoking cigarettes. The risk of addiction to nicotine alone is virtually nil."
Care to link to a study showing dependence in non-smoking humans after pure nicotine dosage?
The modern preference is to use the term 'addiction' for a compulsion to consume or act in a way that will often result in harm at some point; 'dependence' is used for compulsion to consume or act in a way considered harmless by modern urban living standards.
Smoking, given the harm caused by tar and other chemicals would be an addiction.
Consuming just nicotine would not cause harm and this would not be addiction, merely dependence.
Also, tolerance is usually stated as a core factor for addictive drugs. Nicotine does show signs of tolerance. People consume the same amount of nicotine for decades based on the individual, be that a pack a day or 3 packs a day, it stays constant for years.