to avoid disappointment, they also miss a lot of the joy when things are successful.  I presume this is because they are very guarded with their emotions.  Personally, I believe to experience the full happiness of a joyous occasion, you have to open yourself up to the risk of disappointment.  That is too much for some people and I can respect that.

I generally like the curmudgeons I work with and I think most of my associates do as well, there is nothing malicious in their curmudgeonly attitude, it is just who they are.  I naturally have some pessimistic tendencies but I try to overcome them by focusing on more positive outcomes.  Books such as Learned Optimism: How to Change Your Mind and Your Life by Martin P. Seligman helped me tremendously.