Once you understand game theory, poker strategy and/or Sun Tzu's teachings and see that applied in real life, you will understand that pessimism should be the default. However, do not think this means you need to stay timid and passive forever. What you should initially be and do is observant and cautious, waiting for your adversaries to ever fail to be either of those 2 things (observant of threats and acting cautious based on said observations). In simpler terms, you first must be pessimistic and hold out until those who want to take you down or must/can be taken down to achieve what you want fail to be pessimistic themselves.

Here is where we begin to differentiate a cunning and pessimistic underachieving wannabe villain from a proper survivalist who rations their exploitation of adversaries' errors. If you read what I write and teach here and think immediately to go out there and see anyone who makes any error or displays any weakness and to exploit it instantly, you will ironically begin going about things in the way that BurritoLunch (who lied about which side of this he's on) goes about handling people on this website. Instead of making everyone hate you and to assume that any and all errors are there for the taking, you must begin to be pessimistic about your pessimism, since if you are too ruthless that reputation and the urge to hurt you back is sure to doom you more so (or equally so) to if you are totally timid and fail to aggress at all.

Over time, through both your own mistakes and observing the errors of others who try to exploit lack of pessimism in others, you will gain a massive arsenal of nuances and 'finesse' to your techniques. Your implementation of this theory needs to begin to be the inverse of those around you. If you are among pessimists, bait their exploitation of your 'lack of it' for instance, then expose them and don't take the bait to fight back in the same way. That can be enough to doom them to be banned from a website, for instance, or at least begin to trigger them to act worse against you and/or reveal to how biased the mods and admin are in the favour of the perpetrator. Adapt your technique based on what you find. The more they can get away with, the more time you must bide and more enemies you must provoke them to make (and expose them to). Eventually even the most biased in their favour will end up agreeing with you that they are a problem and handle them.

This is only the first 'chapter' on a massive book that I may or may not produce and is of course not the wording I will end up using. This only explains how to handle those who either fail to be pessimistic enough or are very pessimistic themselves in a superficial way. What do you do when your adversary is also adaptive, or is very optimistic and good at gaining trust and having 'shields' that mean they can't be exploited? I will give you a clue; you make the adversary into an ally, or at least that should be your default.