there is this latent assumption here that men are reliable breadwinners and/or that they generally
do not use their economic power in this arrangement to abuse their partners and families.
Women working is a way of evening out the power imbalance that has led to suffering for women all over the world since the beginning of time.
When you have no economic power you are dependent on your husband which is why unpaid labor is so dangerous. The husband calls the shots. Not all husbands are good guys. It's only reasonable for women to want to reduce their exposure to this problem via things advocated for by feminists over time: birth control to avoid unwanted and forced pregnancies (far more common in the days of having 5+ children) and of course death during childbirth, literally their own income stream so they can pay for things a husband might not value equally: healthcare, tuition, clothes, and more, an income stream to enable a divorce should the husband be an abuser, problematic addict or worse...
in less shitty scenarios, the sudden death of a male partner can result in financial ruin for a family with a 'non-working' mother. Again, its economically reasonable for a woman to want to hedge against being stuck at 40 years old with no advanced skills in a career.
It's all about female empowerment.