Despair might be reasonable, but that doesn't make it right. Fight on, because it's the noble and the decent and the best thing to do. Fight on, because there is nothing else worth doing, besides being good to each other. Fight on, because miraculous things happen, sometimes, when you look the world in its dead and broken eyes and say, "I will not stop trying to be kind."
Even beyond hope, there is determination and strength to be found. Cynisism will not save you, it will not protect you, it will not keep you from getting hurt. But if you stand up and say, "I will be kind and just and fair, I will care for my friends and fight for what I need," you will, if nothing else, add a spark of something good to the world around you and to your own life.
And sometimes--not always, but sometimes-- that spark will flame up into something you never could have predicted or imagined. Sometimes the people around you only need a little push to start fighting, imagining, building, changing, and growing alongside you. The best antidote to hopelessness is to start trying to fix things, and the second-best is to watch someone else try.
And sometimes, your actions won't meaningfully change anything, won't do anything but give you a little bright spot in your own life, before being snuffed out again. But that's alright. Beautiful things are not less beautiful for being small.