I assume that you've never heard about rape? Or for that matter coming into contact with HIV positive blood in an accident, or any other infection vector?
Your post implies that if someone is infected with the HIV virus it's their own fault. This assumption is toxic, and makes people more hesitant to apply resources towards trying to treat and cure people with this disease. It's like telling a person with lung cancer that "It's your own damn fault for smoking" when it is perfectly possible to develop lung cancer without ever having a smoke.