Million Dollar Baby : Why does Maggie's mom hate her so much?

Why does Maggie's mom hate her so much?

I already get onscreen that Maggie's mom is so irresponsible that if she would use her siblings to shield herself from bullets. That said even being such an irresponsible dishonest and selfish welfare leech, she treats Maggie with so much contempt that you don't feel towards her other kids. Like with how their relationship was in the movie, I wasn't surprised at all she was trying to manipulate Maggie into giving the family all her assets and she'd just abandon her in the hospital,probably let her die if she runs out of cash. But still even being a greedy lazy scumbag, you can feel throughout the movie a certain hate towards Maggie she just doesn't give towards her siblings.

Why? Especially when Maggie tried to give her a nice new home as a gift and her siblings are unemployed deadbeat losers who just stayed at home all day just like the mother? Moreso apparent in how she doesn't respect her daughter despite making a name for herself as a successful athlete and instead scolds her saying all her neighbors laughs at her for being a tomboy who fights for a living!