I've definitely experienced mental states that were worse than being dead. I don't regret remaining alive because of all the positive experiences I've had afterwards. But if we are talking about extending suffering that's only followed by death, I don't see the point.
I’m wondering if you’ve ever felt debilitating acute pain. I had nerve pain in the past to where my leg felt like it was on fire. It was then I understood how people get addicted to pain killers. I was able to address the problem and I’ve been fine for many years, but it hurt more than any pain I’ve ever had - and I have had many from sports.