Yes we need a reason. life can and will torture almost every human and other animal with diseases, accidents, or old age. One needs a reason to risk these hells such as a threat of homelessness, threat of diseases like cancer, stroke, dementia which most humans are under threat of suffering.
Also one needs a reason a purpose why i have to work so hard, deal with so many problems and sickness, pain , suffering etc.why why? I don't see a reason nor purpose to life.
What is a human or other animal anyway ? just a bunch of trillions of cells. and imo those cells look and behave in a monstrous fashion. if you take a microscope you will see that we are just cells and the illusion fades away