We want to be happy. We want life to go well. Even with reality's complexity and frustration and even real pain, we are programmed to think that things will get better. We want to see the bright side of our time on this Earth.
It's natural, no? With all the pain and suffering and frustration that makes up so much of life, is it too much to ask to occasionally let slip the chains that hold us and feel the goodness? We want to be free to enjoy life, not to be tied down by burdens and complicated problems. So we seek liberation.