> Its very convenient for big pharma to lump all addictions to a chemical imbalance in the brain.
This is also a lazy argument that tends to get a strong response without being meaningful. It's basically equivalent to saying "it's convenient for big speaker that all music requires sound". Chemicals are the regulation system in most living things. They are necessary and that can't be ignored. Some can be artificially manipulated to get desirable responses, hence "chemical imbalance".
I'm also not sure how your examples are relevant to your argument. #1 is a pretty exceptional case, but hard to take as a representative argument. The rest are all secondary effects from human interaction, drugs are incidental to the outcome you describe.
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Ultimately, humans respond to positive and negative reinforcements. This is a pretty primal level thing and can be seen in nearly every other living thing. Do X, receive Y, reinforcement. Living things need these positive reinforcement cycles to thrive. For the most case, these are "mundane" things like talking with other humans, eating normal meals, drinking water, etc, etc. They guide people to keep doing things that make them feel good, even if those things are overall harmful.
GLP-1 drugs are rather exceptional as they seem to temper people's responses to certain reinforcement. Particularly, addictive or addictive-like reinforcements, like overeating. Whether this is the result of a "chemical imbalance" is pretty much just semantics. It's not really meaningful.
They also have some strong, powerful secondary effects, but really only by happen-stance. Patients who eat less, are less likely to develop diabetes. Patients who have less desire to drink alcohol are less likely to develop cancer. Patients who have less desire to do drugs are less likely to become addicts, etc, etc, etc.