The kid isn't at fault and it's amazing that she turned out alright with shitty parents. I mean they are good to her which is the problem since they seem to spoil her and children who get spoiled are the worst. Another thing is that she grew up with those power-hungry parents which is likely to impact her own character. I'm not saying she is great but she seems like a normal person which in its way is great in that environment.
I'm glad the author didn't go for the bitchy spoiled girl gets revenge for the MC harming her parents (even though her parents are shit). I've seen the raws and she doesn't seem to hold a grudge at all