Say you're a married man in the middle or lower income tier, and you and your wife both work, and you know your wife gets paid less than you do even though she's equally smart, talented, educated, etc.

Even if you once held "traditional" views, it's likely to dawn on you sooner or later that the most logical way for your family's income to increase would be if your wife's value were recognized so she would be paid more. This insight would turn you into a feminist (to some degree) even if you weren't before.

If you're in the upper income tier, and your wife doesn't work, because she doesn't need to, then you're probably satisfied with your situation and nothing is likely to make you change your mind.

People in the upper income levels do try to increase their income, but it's more because salary is a status symbol than for practical reasons. Increasing your income by having your wife go to work wouldn't bring as much satisfaction (to the husband anyway) as getting a promotion, because it wouldn't raise your status.

We were all once traditionalists. Those without (much) money have changed their opinions. Those with money haven't.