Unwarranted optimism does.

Being being pessimistic about people in the sense that you don't expect anything good from them will make all surprises positive and in the long run it will help you to not give up.

You can still be optimistic about things without being optimistic about people as it makes it a lot easier to spot the good people and the good actions, if you are positive about people the law of averages and the lack of expected good will invariably and inevitably drown out your ability to notice the good....

Positivity without anything to warrant it will always turn into delusion and self-deceit, ironically not expecting anything will make the most of anything good that does happen by giving it a much greater impact and it also lets you see things more clearly, lying to oneself is the most common of human psychological tendencies....

Unwarranted optimism does.

Being being pessimistic about people in the sense that you don't expect anything good from they will make all surprises positive and in the long run it will help you to not give up.

You can still be optimistic about things without being optimistic about people as it makes it a lot easier to spot the good people and the good actions, if you are positive about people the law of averages and the lack of expected good will invariably and inevitably drown out your ability to notice the good....

Positivity without anything to warrant it will always turn into delusion and self-deceit, ironically not expecting anything will make the most of anything good that does happen by giving it a much greater impact and it also lets you see things more clearly, lying to oneself is the most common of human psychological tendencies....