>>116140050In "Miraculer" HawkMoth targeted Sabrina exclusively because Chloe provoked him. She not only revealed herself, but on every occasion was showing to the whole world how she doesn't care about it and how much she wants to have Miraculous because of that. It allowed HawkMoth to make an ambush for her.
Ladybug explained her why she can't have Miraculous right after danger of it was demonstrated to her. Chloe didn't care. HawkMoth knew it and he did the same thing in season finale. Chloe's parents being attacked was exclusively her own fault, her selfishness and refusing to listen to Ladybug.
Chloe is irredeemable because she doesn't want to be redeemed. She is fine with everything she has and has no reason to change her behavior.
In "Malediktator" she got a bit of self-awareness. She complained that people don't like her, she has no friends and she feels useless. It could've been a turning point for her but it didn't happen otherwise she wouldn't be in this situation in the first place. Instead of dealing with her awful attitude towards people she decided that she could make people like and respect her for being superhero. Chloe remained as she was. She didn't care that people around her could be target for HawkMoth attack. It ended as it should.
Chloe complained about having no friends but it was also a lie. She has Sabrina and Chloe just banished her a few minutes before this talk with Ladybug. Chloe never made an effort to be a friend to Sabrina which farther proves that actually Chloe wasn't improving as a person.
Chloe being irredeemable now just means that she doesn't want to change and no amount of coddling and good talk could help.