There are plenty of people who swear by chemicals like nicotine and caffeine that help them achieve indirect benefits and I can't imagine they're all wrong.
https://www.verywellhealth.com/what-is-nicotine-5075412
" There are many health risks and side effects associated with using nicotine. Some of the health risks include:
Nicotine contributes to the development of emphysema—a type of chronic obstructive pulmonary disease— in smokers.
It’s potentially carcinogenic. Chronic nicotine use is linked to lung, gastrointestinal, pancreatic, and breast cancer.
Nicotine use is associated with peptic ulcer disease (PUD) and gastroesophageal reflux disease (GERD).
Nicotine use increases the risk of hypertension and cardiovascular diseases.
Nicotine use during pregnancy increases the likelihood of complications and adverse outcomes like miscarriages and stillbirth.9
Children exposed to nicotine in the womb are more predisposed to health problems throughout their lifetimes. These health problems affect their endocrine, reproductive, neurologic, respiratory, and cardiovascular systems.9
Nicotine use can cause cardiac arrhythmia—a cardiovascular condition characterized by an irregular heartbeat.10"https://www.cancerresearchuk.org/about-cancer/causes-of-canc...
> Nicotine is the chemical that makes cigarettes addictive. But it is not responsible for the harmful effects of smoking, and nicotine does not cause cancer. People have safely used nicotine replacement therapy (NRT) to stop smoking for many years. Nicotine replacement therapy is prescribed by doctors or is available from pharmacies.
The risks for hypertension, etc is true for nicotine, because it's a stimulant, so same risks exist for coffee. There is very little conclusive evidence that nicotine (not talking about smoking or vaping) has any health effects that aren't also caused by coffee/stimulants.
The best thing you can say about vaping is that it's very understudied and long term effects are unknown, and likely has some long term effects that are bad for you.
Smokeless nicotine (swedish snus-variety) is considered very safe.
The problem is smoking and nicotine have been so intertwined for so long that when they say "Nicotine causes x" most of the time what they mean is "Smoking causes x" and maybe also "Vaping could potentially cause x"
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4553893/ "In several in vitro experiments, it has been found that nicotine in concentrations as low as 1 μM decreased the anti-proliferative and pro-apoptotic effects exerted by chemotherapeutics on several different malignant cell lines"
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4363846/ "There is decreased immune response and it also poses ill impacts on the reproductive health. It affects the cell proliferation, oxidative stress, apoptosis, DNA mutation by various mechanisms which leads to cancer."
Are you a big vaper or something and this is upsetting to you or something? I can't see any other reason for you to react with outright lies.
I think the main problem with nicotine is its addictiveness and the fact that that will lead you to accept risks in administration via cigarettes, toxic fluid vapors, chew with fiberglass, etc.