The antagonist of "The Rocking-Horse Winner" by D.H. Lawrence is Hester, Paul's mother, and she is unlucky because she chooses to see herself as unlucky. The opening lines of the story make it clear that she was not unlucky from the beginning; in fact, she had lots of privileges others never have--until things go awry.
There was a woman who was beautiful, who started with all the advantages, yet she had no luck. She married for love, and the love turned to dust.
Because she was beautiful and had "all the advantages" of life, she had the privilege of marrying for love rather than for money or something else. Nevertheless, her love soon vanished. Though we do not know what, exactly, caused her love to disintegrate, we know it was probably her fault rather than her husband's, based on her feelings for her children.
She had bonny children, yet she felt they had been thrust upon her, and she could not love them. They looked at her coldly, as if they were finding fault with her. And hurriedly she felt she must cover up some fault in herself. Yet what it was that she must cover up she never knew. Nevertheless, when her children were present, she always felt the centre of her heart go hard. This troubled her, and in her manner she was all the more gentle and anxious for her children, as if she loved them very much. Only she herself knew that at the centre of her heart was a hard little place that could not feel love, no, not for anybody.
She does not seem to know herself what has caused her heart to harden to such a point, but we do know that what seems to have replaced it with is an insatiable desire for money. She buys things in an attempt to satisfy her empty, hard heart, but these things never fulfill her.
One incident which might serve as an illustration of how good things turn bad for Hester is the surprise birthday gift she receives. Her son, Paul, arranges for her to anonymously receive five thousand pounds, one thousand a year for the next five years. This is a delightfully unexpected and generous gift, and Hester should be thrilled and grateful. Instead, her first and only reaction is to wish she had all of it at once. No gratitude, no thankfulness, no joy. Given this example, it is not particularly surprising that her love has become dust and she sees herself as unlucky.
Hester is a spectacularly negative, dissatisfied, and unhappy. She has a lovely family, a fine home with lovely furnishings, and everything else money can buy; however, she is not content with any of it. Her love "turns to dust" because she is never satisfied, and that is also why she believes she is unlucky.