Everyone makes their own decision based on their particular circumstances and as long as it works for them, why on earth are you, OP, being so ruddy judgmental?
So you are intrigued as to why people have children just to hand them over to someone else and would like the rest of us bad mothers (because it's clear that's what you think we are for working) to enlighten you? Do you have so little imagination that it's beyond you to understand that we might have them for the same reasons as you? We just choose, or have, to live our lives differently, whether for financial, personal or professional reasons - and that doesn't make us terrible or neglectful parents. It makes us good parents because we are trying to do our best for our families, in just the same way as you, I assume, are trying to do the best for yours.
But your question, while it might not make you a bitch, does make it clear that you are supremely smug about your own choices, and naive about other people's.
I grew up poor with a mother who stayed at home, and no, we weren't happy despite it all. We hated wearing last year's winter coat, or not going on school outings, or having a family holiday once every four years. And my mother missed out on having a career, which she still regrets to this day. So I won't apologise to you or anyone for choosing to work full-time so that we can have holidays, buy what we like and save what we can.
I don't criticise anyone for doing what they think is right for them and their family, whether it's being a SAHM or WOHM, or breastfeeding, weaning or sleeping choices, and all the other crap that brings out the judginess in people. Everyone does what they can, and we'd all be a lot better off if sanctimonious types like yourself learnt to be a bit more understanding and accept that Not Everyone Is Like You. Or Wants To Be.
BTW, you haven't name-changed from littleamy, have you, OP? I seem to remember a boringly similar thread in this vein, started by someone just as unenlightened as you, from a few weeks back....