By product is WATER VAPOR! The only things in e juice are: Propylene Glycol, Vegetable Glycerine (BOTH found in foods and beverages as well as some liquid medications), flavorings (widely used in foods, candies, cakes, beverages and the like) and nicotine IF the vaper wants it in there. Period. THERE ARE NO CHEMICALS as with cigarettes.
As for calling it an "addiction", that's pretty strong language. Most vapers used vaping to ESCAPE THE ADDICTION of cigarettes and the 3000+ chemicals known to be in them. Please do not confuse the two.
A habit, now yes, it is a habit. A cleaner smelling, better tasting habit than cigarettes.
Just my 2 cents.