I stay at home because I have liberal arts degrees. I was an editor. I made 1/4 of what my husband made pre-tax. And with the marriage penalty I got taxed at his tax rate and I did the math one day and figured out that I was working for less than minimum wage and my salary was paying my husband’s taxes. All this for a job I didn’t love.
Then I got knocked up (suprise!) and any salary I might have made would have gone to pay for day care if I didn’t stay home.