Wow. My experience of depression is so incredibly different than yours. I do live a “good life” and I have been depressed for most of it. How could I be living an “unfulfilled” life when I was 8? Certainly one can exacerbate depression by living a life one hates, but let’s be clear, there is clear evidence that there is a strong genetic component to depression. I got them it my Mom, along with 40 years of migraines.
In this case, no, hanging on was just not an option. My experience is that it can last forever. I strongly believe now, at 62, that my depression will be with me forever. Luckily, I have found a way to deal with it so that it’s not overwhelming — it’s kind of like watching a sad movie — it’s clear that this all worked for you and, to paraphrase Hunter Thompson, I wouldn’t recommend it to everyone.