But why does the victim feel shame?

Victims feel guilty for not preventing the victimization. Even going so far as to consider that they may have caused it in some way, or somehow were deserving. In the case of crimes such as sexual assault this is emphasized by the social stigma of being “impure” after an attack.

https://psycnet.apa.org/record/2021-82681-001

Why is the public response insulting the victim for being a victim?

One reason is because people do not want to consider it could have happened to them. By pointing out where a victim went wrong they distance themselves from the similarities between themselves and the victim.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9455198/

There is much speculation because people are not often willing to admit to victims blaming so getting at the roots of this behavior is difficult.

But why does the victim feel shame?

Victims feel guilty for not preventing the victimization. Even going so far as to consider that they may have caused it in some way, or somehow were deserving. In the case of crimes such as sexual assault this is emphasized by the social stigma of being “impure” after an attack.

https://psycnet.apa.org/record/2021-82681-001

Why is the public response insulting the victim for being a victim?

One reason is because people do not want to consider it could have happened to them. By pointing out where a victim went wrong they distance themselves from the similarities between themselves and the victim.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9455198/

There is much speculation because people are not often willing to admit to victim blaming so getting at the roots of this behavior is difficult.