I think the main problem we view depression as a disease when it is a symptom with several possible causes. Most people I know haven't done the deep introspection when life circumstances or past in some cases preverbal traumas exist.

Additionally, we're generally told quite a lot of lies and made to believe fantasies from the earliest ages about - the world, who we are, and our place in the world. I have a theory and it's just a theory when we get misaligned with certain, let's call them, cosmic truths - there's a mind and body reaction, often outside of our conscious ability to recognize the problem.