Prostitutes set themselves up for violence. The fact that many prostitutes are intimidated by the police prevents them from reporting acts of violence against them, and perpetrators know this. Anti-prostitute laws and social attitudes set prostitutes up for violence.
Prostitutes are victims.
This victim mentality is a convenient way of absolving oneself of blame for making ill-conceived or unwise choices. Typically applied to female rather than male prostitutes, it reinforces the archaic notion that women don't know what's good for them and are incapable not only of making their own decisions, but also of taking responsibility for those decisions. All prostitutes are survivors of childhood sexual abuse. Even for those who are, that doesn't mean that they are incapable of making decisions for themselves. Prostitutes need to be saved from themselves.