I started on and off socially from 15. Really picked it up speed after a horrendous breakup at 28 which nearly killed me. Stopped outright at my first pregnancy aged 34. Now I'll very very rarely (once or twice a year) have a wee puff of a rollup.
With the benefit of hindsight I can see what it was doing for me.
I'm autistic, and didn't have friends or connections at 15 - it gave me acceptance into a 'club' where sharing of resources (kindness) in terms of borrowing and lending cigs, lighters, and when the smoking ban came in, there was an opportunity to chat to someone for a fixed e.g 5 mins in a quiet place.
I'm ADHD - and similarly smoking gave me opportunity to leave a busy, overwhelming pub or club for a window of brain space.
And at the end of a long day, they gave my wildly buzzing brain the excuse to stand outside, in the dark and the quiet deep breathing.
It's easy to say you can do all of the above without cigarettes, but life is full of things that don't happen until you have something to hook them upon.
I don't think I was ever, or have ever been addicted to nicotine. I have never 'craved' in the way that has been described to me.