You should really be more careful taking things that people say as a personal affect on you, or people like you. It is ok for people to talk about their personal feelings/beliefs/experiences without it being value judged by you (as rude or narrow minded).
Not every message is meant for you.
If a depressed person genuinely thinks their life is good and that they have everything going for them, this is often from lack of realisation or self deception.
To pick an easy example, someone who's got a successful well paid big city career being depressed, because internally they don't want that and just did it because others told them that's the path to happiness, and they've repressed their subconscious desire to say raise a family in the countryside instead.
> Once your life stops being shit, you stop feeling depressed.
You really should be more careful trying to shoehorn everyone with a medical condition into your shoes. You come off as terribly rude and narrow minded when you do so, which I am sure was not the intention. People who live perfectly good lives also suffer depression. People who have everything seemingly going for them suffer depression. And yes. The focus on brain chemistry is warranted, it’s based in scientific observation, discarding it just because your personal sorry doesn’t align is like discarding vaccines because “I never got vaccinated and didn’t die from covid” you are just one datapoint in the collection, and no matter what your experience is, you can’t blankly extrapolate to the entire population.