"Why, in the last two cases, does decreased emotional health lead to increased abuse from other people? " quote pachyderm

That is because "victims" can utilize "defence mechanisms" that can "attract" people who are "abusive" or as often stated, "hurt people, hurt other people".

If a victim developes "defense mechanisms" where they appear stronger, or more "intellectual" or even will be the one that points out bad things, they can often draw others to "challenge them" and want to "put them down" because it seems like they are putting themselves "above others" or are "stronger then they actually are".

Or, a victim can be "timid" and can be quiet or look like "easy prey" to someone who is "abusive" so the "abusive" person will pick them to be a victim. Sometimes this also happens because the "abuser" is "repulsed" by this "victim mentality" because it reminds them of a part of themselves that they "hate".

Another example could be: Lets say a man was raised by a naricisistic mother and no matter what he did to try to "please" or "gain natural approval that all children want" his mother never showed him appreciation and love. What can happen is that "any woman" that "reminds him of his mother" can become a target. He may try to "please this other woman and gain adoration" because when someone is "tramatized" or "neglected" it is "normal" to want to finally "resolve that trama or neglect" so that "healing or a sense of overcoming can take place". So, what can happen is there can be a "testing" or "unhealthy interactions" with this woman that reminds him of his mother that can lead him to think he is "again" facing rejection or failure. So, he may then want to try to "discredit" or "invalidate" this woman anyway he can, it can become an "obcession" even. Unfortunately this man can become very "confused" about women, and never be able to actually "have" a good relationship with a woman.
It can spiral down into him even experiencing "crippling anxiety" of somekind, even having a strong sense of "personal failure" that he can't quite seem to "fix". This scenario can also be replaced by a woman instead of a man going through these "unhealthy attempts to overcome neglect from a father".

Unfortunately pachyderm, when someone is "tramatized" or "neglected" they will be constantly setting goals to find a way to "resolve" that trama or neglect. We are "all" designed to do that in order to survive. Unfortunately people can get "skewed" and not understand "how" to "fix" whatever "hurt" them and they can try to "settle the pain" in some very "destructive ways", even self harming or becoming a "bully" or hiding the pain in "narcisism".

When I talk to people who have been victims, or have been neglected and are struggling. I tell them to look "behind" the person who neglected or abused them so they can realize it was not due to "their" lack of worth or weakness. Instead the person who neglected or hurt them had themselves experienced "personal injury or neglect or pain" of somekind which inturn made them, inadequate or incapable of properly nurturing their child, or even appreciating others in "healthy" ways.

Often, victims can be drawn to others who appear "strong" where they feel they will somehow be "protected" and what they actually might pick is someone much like the person who abused them, and their appearance of strength is not "true stength" at all, instead they can be a very "selfish and a highly narcisitic person" who constantly dominates and even can "victimize and control".

Another thing that can happen is that a woman may pick someone abusive like their father unknowingly, it seems safe, something is familiar, something looks like something they know how to live with etc. However, they discover, often much too late that all they did was marry a disfunctional man just like their father. That happens alot.

Are you starting to now see how a victim can be respeatedly a victim? It is not something "intended" but how being a victim can lead to experiencing more abuse.