Patriarchy is a zero-sum system. Someone has to be the one-up and the other person the one-down in any interpersonal interaction. If you don't "win" you "lose." Those who are still bought into that system don't want to feel like the loser, which they are measuring by all kinds of superficial metrics such as power, wealth, and status. Women who make more money than their husbands typically do more of the housework than couples with even incomes or where the husband earns more. He already feels emasculated by her earnings (and/or she feels self conscious about doing that) and so makes up for it by doing more "women's work."

Fortunately, there are men out there who aren't bought into this system, and who aren't threatened by strong, successful women, but they are in the minority because when you take your sense of self by always comparing yourself to everyone around you, you tend to be really insecure - and that's what the prevalent culture still messages. Thank goodness for the men (and women) who are beyond that!