Sorry it wasn't clear, I was not advocating for anything here, certainly not that people should smoke to prevent dementia.
Large quantities of nicotine are poisonous (just like caffeine) and it is addictive (more so than caffeine).
Regarding cardiovascular health, I'm not sure. As far as I know, nicotine itself is safe unless overdosed, but smoking and vaping of course is unhealthy.
I like coffee, and drinking to much of it is also unhealthy.
However, I love to remind myself of all the pop-sci articles saying that 2-3 cups are healthy when I'm making myself my 5th or 6th cup for the day.