In many of these cases I believe, the person hoarding the cats started with the best of intentions, I know/knew of such a lady.
She was just so upset that the SPCA etc was killing these beautiful animals, that she wanted to do something about it, for years she did a very good job, over time people dumped so many animals on her that she became overwhelmed, did not know how to say no to people, and may have snapped.
Some years ago, I was in the line at the grocery store.
I was behind a woman who was buying several plants that appeared to be dead. I told her she should go back over to the plant department because I saw some nice ones over there.
She said that, no, she wanted those because if she did not buy them “nobody else would”. She was planning on nursing the dead plants back to life!
It is some sort of misplaced altruism.