How do men have sex with others who have hiv and they know it?

Foolishly: Many people engage in behaviors which are known as potentially harmful (smoking, drinking, cheating on exams, using illicit drugs, etc.). While doing these things the factors driving their actions may outweigh logic. In the case of HIV disease, many gay men have intentionally exposed themselves so as to fit in with the remainder of their local community. Denial is a strong phenomenon.