Wouldn't INFPs be even more prone to be targets?
I would certainly think so. INFPs seem to paint the target mark on their foreheads.
From my experience, I've had several toxic people in my life. My parents, both mentally disturbed people, were extremely toxic.
My INTJ father is narcissistic and sociopathic. He thinks he is a god, literally, and expected all of us to worship him. He told my stepmother to address him as "King" and so she does. Mental and physical abuse came with his "entitlement" issues. If we displeased him in any way, even something so small as spilling a drink or forming an opinion different from his, we were sure to get 1. beaten or 2. verbally assaulted. My father once flew into a rage and actually BIT my brother's finger because him sucking on it (at 1yrs old) infuriated him.
My ESTJ mother, also very toxic and mentally disturbed, was actually put into a mental institution when she was 16. She hasn't grown up past the age of 16 and is incapable of thinking of anyone outside of herself. She wants approval from anyone who will give it to her, and manipulates those around her to get that approval/attention. I feel sorry for my mother.
I find that toxic people attract more toxic. During those years I was toxic, I knew a whole lot of messed up individuals. Girls who were raped or tried to commit suicide were my friends, boys who were abused or abandoned were my favorite pals to hang out with. I was attracted to toxic people because toxic people was what I was familiar with.
So, if an INFJ only knows toxic, I think they will be a "target" for toxic people. But then, I think that holds true for ANY type. I still think INFPs are more prone to being "preyed on" because INFPs are such selfless healers.