Positive comments about nicotine in the LessWrong community were a major reason why I started vaping. I found the addiction to be less serious than commonly claimed, but I also found the beneficial effects to be small. I couldn't say with confidence that it's better than caffeine, and caffeine is more socially acceptable. I don't suppose I'd be shadowbanned for telling people my experience of caffeine.

In my own experience, nicotine was not very addictive. As a non-smoker, I started vaping 36mg/ml nicotine in unflavored propylene glycol. I used a high concentration to minimize exposure to any unknown non-nicotine risks. I vaped heavily for about 2 years before getting bored of it. I tapered the dose to zero over two weeks and experienced only mild withdrawal symptoms. It's been about four years since I quit and I've never felt the effects were sufficiently interesting or enjoyable to start again.

I vaped unflavored nicotine for about 2 years. Intermittent at first, heavy daily use during the second year, equivalent to a pack of cigarettes per day or more. I quit because enjoyment decreased to the point where it was no longer worth the hassle.

I experienced zero addiction for the first three months, and even after the full two years addiction was mild. I reduced my dose gradually over two weeks. There were no physical withdrawal symptoms, and only minor craving which went away after a few months abstinence. I'm no expert on heroin addiction, but I find it hard to believe it's equal to nicotine. Perhaps whole tobacco would be different.

No, the difference is, at least from what I've seen (am not sure if the research supports this, but it would be interesting if it did not), some people (like myself) seem to be more susceptible to smoking addiction than others. I know quite a few people who have no trouble smoking intermittently, with months in between, and then quitting with hardly any effort. Maybe they just have more resolve or willpower, but I've seen them smoke more than enough to "catch" the addiction like I did, then stop, never really getting stuck into a daily habit. Yes I'm jealous :) On the other hand, I don't want to smoke just "occasionally" either, I just want to quit.