Nicotine on its own causes very little harm.
(A word of advice, though, if you decide to read up on this topic: it is extremely common in the research literature to lazily conflate tobacco with nicotine. You will routinely find abstracts which say something like 'we sampled smokers...' and then in the conclusion write '...we conclude that nicotine damages cognitive performance', as if tobacco was nothing but solidified nicotine. When you find something negative about nicotine, you need to check that tobacco is not driving the results.)
Also nicotine effects are more isolated to brain. Caffeine affects whole body including metabolism stimulation and hearth rate. Not so good for office worker.
It is also assumed that the tobacco is burned. Sure, snuff can cause oral cancer (unlikely though it may be in comparison to cigarettes), but if you dodge the oral cancer bullet what are the other potential problems? I have no idea because everything I find conflates tobacco use with burning it and inhaling it. Smoking is bad, we get it. Smoking automotive tires is probably bad, too. How about the effects of tobacco itself, separate from the bad effects of burning something and inhaling it?
Nicotine is ambiguous.
Not really. Nicotine seems to be about the same or maybe a few times as dangerous as caffeine, which is to say barely dangerous at all.
Most of the danger of cigarettes is burning the plant material. There is a study assigning cancer risk to the toxicants of tobacco smoke and there is a list of the top 50 or so chemicals of concern called the Hoffman analytes. Nicotine isn't on this list.