chemical imbalances are very real, its just that the cures dont actually help you alleviate those imbalances. On a intuitive level, it makes sense that any chemical that you introduce to your body (be it drugs, or even just food) creates an imbalance that your body tries to compensate for, since your bodys main goal is normalizing its internal state. Most pharma drugs are band aids, which dont actually cure the root causes, leading to dependence in order to feel normal. even just an unhealthy lifestyle causes chemical imbalances, it doesnt have to be a drug you take. the detrimental part of this is that some drugs can temporarily cover up the imbalances as well, which leads to people reaching to these drugs to 'feel normal' - this leads to what we would call addiction, because addicts mostly self medicate. the drug doesnt have to be the root cause.