Spot on, dopamine isn't addictive. It is the mechanism by which addictive behaviors are reinforced and ingrained into neural pathways. To say dopamine is addictive is akin to saying alcoholics are actually addicted to the processes of fermentation and distillation. Dopamine itself isn't pleasurable like many people believe. Robert Sapolsky states, "dopamine is not about pleasure, it's about the anticipation of pleasure; it's about the pursuit of happiness rather than happiness itself." [1]
GABA is an interesting candidate, but we must also consider the effects of endorphins, norepinephrine, oxytocin, endocannabinoids, and perhaps other amines as well. With sufficient release of certain neurotransmitters, there is likely a cascade effect where others are released in turn. It seems like any powerfully rewarding and pleasurable activity is going to cue the release of some or all of these neurotransmitters/hormones (the line between them can be blurry; under certain circumstances, neurotransmitters get dumped out of synapses and into the bloodstream to become hormonally active in the body).
Perhaps there is even some coding between different mixes of the above chemical messengers and the distinct subjective types of pleasure, such as deep satisfaction, social harmony, social ecstasy, family bonding, sexual release, elation over a personal victory, etc.
But I want to take an even further step back and appoint to an even more fundamental cause of receptor density changes, and that is oxidative stress. I believe the oxidative stress is the underlying mechanism of addiction. If you can manage oxidative stress, you can inhibit addiction.
I love this definition, because we feel the absence and want to resolve it. If the focus on that absence gets too great, we start living to serve the reduction of that absence, leading to antisocial behavior the deeper you step into the addiction.
I also believe this is one reason why we are so easy to addict these days - we feel the absence of meaning in our lives (which used to be filled by spiritual practices that many have abandoned all over the world) and in an effort to reduce that lack of meaning, we seek meaning in other things. And if not meaning, we seek comfort which can lead to addiction to anything we rely on too much to salve the pain.
This is a philosophical take rather than a biochemical one, of course, so there are multiple angles to consider this issue from.
GABA analogues are just metabolized a lot in the gut and do not get into the brain as easily as triggering the release via dopamine and serotonin agonists.
People don’t get addicted to dopamine, they get addicted to GABA.
https://pubmed.ncbi.nlm.nih.gov/23034651/#:~:text=GABA%20is%....