Why not? By my thinking a pessimist and a loser are the same thing. Who truly wants to be a loser. Thus, who would choose to be a pessimist. The most basic combat principle- if you assume you are going to be killed, you will hesitate to do what has to be done to survive. So in the real world, a similar principle applies If you succumb to your assumption that it’s all bad, you will not pursue what is good.