I find this sort of stuff really interesting to read about. Maybe because I have so many family members that have dealt with addiction.
Always something I have to keep in mind every time that I gamble or do anything that might turn into addiction.
In reality, all of these amount to a chemical dependency due to the physiological changes that occur in the brain. Certain actions lead to the releases of endorphins, dopamine, serotonin etc that can trigger a pleasure or freedom from stress response. In the end, everything boils down to the neurological reward system, with all of these factors being triggers for reward, or aversion to stress (sometimes caused by lack of reward).
It's also pretty fascinating that in terms of brain chemistry, you don't see a difference in chemicals that are released. Whether you're addicted to a substance or a non-chemical activity like gambling.
I do hope we'll eventually figure out how to combat addiction more effectively, there's some really interesting research going on in that area too.
I've read some promising research, that might be able to completely remove the need for certain substances (also gambling), by magnetic brain stimulation.
Here's an article about that:
http://www.sciencemag.org/news/2017/08/brain-altering-magnetic-pulses-could-zap-cocaine-addictionAlso worth it to look it up on Google Scholar and see the original research.