What if it happened to you? Your wife, daughter, sister, mom? Opinions would change if you had to sit and hold a loved one's hand in doctor's office waiting for an HIV/STD test because of an assault, or the police calling your home after a loved one was found drugged, cut and unconscious on the side of the road.
Even if the perpetrator is caught, the victim still has to sit in a court room and relive their experience over and over again in front of people. Many true victims never even pursue the rapist because of the process to convict itself.
Hate on me for being a gun owner, but the above scenario will never be me or a loved one of mine. If an attempt to rape is made, the victim has no way of knowing if the rapist has AIDS. So yes, the victim's life is threatened in this scenario.
Don't misunderstand, if someone I loved or myself did become a victim, I would not go looking for street vengeance but I would use lethal force for prevention.