"The world is made up of three types of people: Type Number One's who understand and openly acknowledge that they always act in their own self-interest.....Type Number Two's, who understand that they always act in their own self-interest but try to make you (and others) believe otherwise....and Type Number Three's, who either don't understand or don't want to understand that they always act in their own self-interest. Beware Type Two's and Type Three's."
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Type Two's will deliberately hurt you. They are thieves and con artists and liars and cheats who know their true nature is so dark they must carefully conceal it.
Type Three's will unintentionally harm you. Because they are constantly at war with themselves, denying their true nature, making decisions based on delusion rather than reality, they will inevitably string together enough bad decisions made for the wrong reasons to destroy themselves along with anybody standing around in bomb-blast range.