Why do people use tobacco, anyway? Nicotine, the most important active material present in tobacco, is highly addicting, mildly euphorient (that is, it makes people "feel good"), mildly appetite suppressing, and a drug that causes changes in alertness, level of anxiety, and concentration. Smoking is also a horribly dangerous habit, easy to start but devilishly difficult to stop because of nicotine's strongly addicting nature. Only about one out of 20 smokers who try to quit unassisted will succeed after a year has gone by.