It's a very psychological addiction. Obviously willpower and compulsiveness vary depending on the person, but whether you believe it is easy to quit or hard to quit, you are right.

The misery of quitting comes from wanting something you cannot have. The trick to avoiding that misery is to truly not want it. Then the only remaining struggle is a few days of noticeable physical symptoms (like having a mild flu, at worst) and the long struggle of trying to not forget why you don't want to smoke or vape or snus.

Anyone wishing to quit should read Alan Carr's book. Don't worry about whether everything in the book is literally true; the point of the book is not to be a list of pedantically true statements; the point of the book is to get you to quit smoking.