I am surprised that no one has mentioned spite. I have been used, abused, abandoned, taken advantaged of, thrown to the wayside, etc. and to finally kill myself will bring nothing but joy and blessings to all those who have wronged me. The mere thought of this is enough to feel like I need to "win" somehow. I can't let them have the last laugh.
Though as I get older, the fire that fuels this anger and spitefulness burns colder and colder. There have been times where it was reduced to embers and I felt utterly vanquished and defeated. It was an incredibly surreal feeling; one where I literally did not care about anything anymore. The people I hated the most could torture me and I wouldnt even fight back. My ego, the last bit of self preservation and dignity, was almost irreparably shattered. Scary times.
Although indeed I can be "too angry to die" sometimes, it is still just one factor. There's quite a few others that may have been mentioned before like ambivalence, fear, laziness, etc. I just wanted to mention this.