People commit crimes for several key reasons: to fulfill needs due to poverty or illness, because of psychological issues stemming from domestic violence or mental illnesses like schizophrenia and kleptomania, or due to human emotions such as competition, jealousy, or love. The document outlines reasons for crime including fulfilling needs due to despair or lack of money, psychological problems from domestic violence or mental illnesses, and human emotional outrage from competition, jealousy, or love.