What else? Personal experience. Fundamentally, it's down to the individual how much value they attach to their own life, so if someone else is in the same boat as me I'm not going to try to argue them into feeling their life has value. But on the other hand, treating others as if they're valuable makes most people feel better and helps society maintain itself better than the converse. I just don't think there's much to be gained for either society or myself by keeping someone who has the double-whammy of both MDD and dysthymia alive. The upshot of having both these conditions at once is that I basically cycle between bad periods and worse periods. Feeling lousy is my baseline.