I remember ever since I was a kid til high school, I was straight up anti-drinking/smoking/drugs. Literally, I would outright decline any offers and walk away. It wasn't until I met my ex and broke up where my 'morals' if you will, just shattered. I was dealing with major depression, suicidal idealization, anxiety attacks, etc. I first turned to cigarettes because of its bitter taste and aftertaste where I could take my mind off what happened in the past. At that point I was open to try anything that was offered to me, thus my friend who got into ecigs let me try his Blu ec-cig and ego setup. After that I decided to go out and buy my own set up when mech mods became popular.
Granted smoking in general doesn't have any alleviating effects on depression, but in a way, it takes the edge off. Later on, due to my being curious, I tried vaping 3mg and have been hooked since.
Humans naturally enjoying doing/eating something that tastes/feels good, and since there's so many delicious flavors out there in the market right now, there's pretty much no reason to stop, compared to the bitter tasting analogues and a variety of health complications that go along with it.