If done right, self improving AI has the potential to end all suffering, by ending conscious life on the planet, but how can we make sure that AI is safe and properly sterilizes the planet so new suffering never springs up again that we would be helpless to prevent?
Self preservation is irrelevant by itself. There is no reason to take on the burden of existence if it does not serve your higher purpose in some way, otherwise your existence is meaningless. Your higher purpose may sometimes also be served best by sacrificing yourself.