See, as a parent one of the biggest things for me is also retaining my sense of who I am, and who I have been for the thirty three years before I had my first DC, and staying happy - which as much as my DD is the best thing that has happened to me, includes working. And it includes knowing that I am not counting every penny at the end of the week to see if we can afford to buy an ice cream on the way home from the park, not budgeting our meal plans so tightly because we have a tiny amount to feed ourselves on, all of which would happen if we went down to one salary.
Some people will call that selfish, others won't.
I certainly don't see general criticism (not just on this thread, but in life) aimed at my DP for wanting to continue working f/t in a very challenging, difficult and potentially dangerous job that has knock-on effects on our family life, a job he can very rarely leave when DD is ill. Not one person in RL or online has said, how could he possibly consider doing that job when he has a young child? But plenty of people, in RL and online, have made comments to me, the mum, about returning to a f/t desk job that I can, realistically, dump and run from when DD needs me.
Also who knows what your child's needs are to make them happy? Many kids in childcare adore their childcare. Mine worships her CM and has close friends there. Now, she would be upset if she didn't go back, she would miss the socialising and the being with her friends that I couldn't offer her by being at home. That's just my child, other children will be different, but who can happily say that mum being there all the time is exactly what every child needs?
I could rant much longer. But it comes down to what I have said time and time again on here. Why is wanting some financial security and to continue using the education you worked so hard for considered selfish?