Depression has many causes. For many it is purely genetic and biological, something wrong with the brain. For others it is past abuse, trauma, etc. Meds and therapy help you get to a place that you can work on those issues. Trauma and abuse changes the brain. I can give you a 20 year list of things I have tried to cure my depression. AA Alanon, CBT DBT therapy counseling meditation exercise you name it. I spent many years working on my issues and baggage. My depression still comes and has gotten worse. They know the brain is broken they just don't know how to fix it. Meds work in about half the people. I have very treatment resistant depression. Meds don't work that good for me. Sometimes they do though. Currently my meds are making a difference.