It's worth mentioning, since most people don't know, that nicotine on it's own is not as addictive as tobacco. AFAIK the MAOIs in tobacco smoke contribute more to its addictiveness than nicotine [1]
I've been chewing nicotine gum semi-regularly for a few months to improve my focus at work, and have not found it addictive so far. (I've never smoked).
(Still, I wouldn't recommend people in general do this without carefully considering the risks.)