There's no question that nicotine is a drug, and just like almost every drug out there, different people react differently to it.
It's a stimulant until it isn't. This happens relatively rarely, but there have been times when I've woken up in the middle of the night and not been able to get back to sleep until I had a puff or two from the vape I keep on my night stand. OTOH, when it's time to wake up in the morning, it lifts the fog out of my brain more quickly than the coffee that soon follows.
Cigarettes are less of a stimulant that straight nicotine is for a number of reasons, not the least of which is the carbon monoxide they put in your blood, which displaces oxygen. Then there are the other alkaloids and MAOIs in tobacco that produce some relaxing effects. The latter effect is immediately obvious to me via a good WTA liquid or an iqos.
My Mom.. she's 91 bless her and just stopped playing Tennis a few years ago.. (I Hope I have her genes) says the same about Coffee!! I Don't get it at all.. I used to love Lots of Expresso but now.. even decaffeinated coffee gives me jitters and upsets my stomach. I guess it's just another sign I'm getting to be an old fart. LOL She'll wake up in the middle of the night drink coffee and it puts her to sleep!