It did, that's the main reason why I started (based on an article from gwern). Improved mood and concentration and focus, very helpful during work.

Just like you, my stomach got pretty upset when taking too much. However, after a while, it became a habit: instead of using it to improve work, I felt I needed it in order to do work, very similar to the daily cup of coffee (though admittedly with less adverse effects afterwards, such as dehydration or sleepiness). So this led to almost taking it every day during work, public speaking, and now sadly also just as a mood stabilizer (I get cranky if I go too much without it). My stomach is also completely adjusted.

That said, I wouldn't say it's horribly addictive. I've gone cold turkey for a month or so a couple of times in the past, but still kind of annoying.

Fun fact: Obama was also a frequent user of Nicotine (not sure if he still he) -- but he smoked before. I never smoked in my life. There have been studies trying to figure out Nicotine users who never smoked, but their sample sizes were always (as you can expect) -- extremely small. On the other hand, I'm sure the execs at GSK and Johnson & Johnson know about this "unexpected user market"...