Addictions can ruin the lives of those who have them and the people around them.
People die from lung cancer and give other people asthma by smoking. Alcoholics and illegal drug addicts cause more problems in our society than I can count. Even medication prescribed by doctors can cause addiction, though the help they give may outweigh that.
I understand addictions work by creating chemicals in the brain similar to the natural ones are generated when people feel pleasure. Those false sensations may be more intense than the natural ones.
However the brain stops making the natural chemicals as a result of getting the others, so addicts can only feel pleasure when they're high or drunk. If people get into recovery their brains do start making the pleasure chemicals again, but it make take quite a while before that happens.
However there is one good kind of addiction. An addiction to reading!
Reading can stimulate all sorts of emotions, but those feelings are natural even when they're caused by reading fiction. A good plot may give the reader fear, excitement, frustration, relief, peace and joy, to name only a few feelings gained from books.
To be honest, I must admit that I'm a bookaholic and I have no intention of ever getting into recovery.