I know why Low chooses to come here and be an ass. She loves to bully the people who don't fight back hard enough, or in this case, us. She likes to put other people down to make herself feel better. This is because she has low-self esteem, and is generally depressed. It's truly sad that she was raised this way, with heavy depression and bad friends/siblings. So instead of being mad at Low/Howl, feel pity for her, and her life so far.
And also feel bad for the parents, because they are probably good people, disappointed that one of their only children was a bad apple.