Why is life such a dark and doomed experience?

Well, that's just the way things are and there isn't much you can do about it. You can't worry too much about it or else you'll go crazy. Sure it is depressing and unfair but you can't let yourself be consumed by the things that you can't control especially the if those things don't have a direct effect on you which is usually the case. The world isn't going to change, it's been this way for thousands of years. Worrying and griping over the problems of the world will get you nowhere and it certainly won't improve the state of the world. Just do your part to to make the world a better place by being a nice person and helping other people when you get the chance and maybe it will improve the life of others around you and maybe even your own. But you won't be able to save the world, so don't worry about it. There is nothing you can do to eradicate the evils of the world so there is no reason to worry about them. You must learn to focus on only the things that are within your control in the present and to accept the things that you can't control or no longer can control. If you can do this you will be a much happier person.