OK, but that's just work, and people work hard all the time, I've heard. You learn to manage your time better, you sleep a little less, you drink in the shower, and so on. People have been keeping babies alive for thousands of years, so even an idiot like me should be able to manage. But the workload itself isn't the really frustrating part. The part that will really tear your curly hair out is how the person you're doing all this work for is incapable of appreciating it or conducting any type of communication other than ear-piercing screams. Imagine being in hour 20 of a typical 18-hour day; you're tired, hurt, and annoyed, while the person you're trying to help is screaming, "FUUUUUUUUUUUUUUUUUCK YOOOOOOOOOOOOOOOU," directly into your ear. I don't care how much genetics say you're supposed to love the little monster, that isn't fun.
Incidentally, I'd like to apologize to every waitress whose ear I've screamed, "FUUUUUUUUUUUUUUUUUCK YOOOOOOOOOOOOOOOU," directly into.
It's a serious issue, actually. Kids can spend a lot of their first two or three months crying inconsolably, and parents have totally lost their cool about it. My kid wasn't even that bad, and I had to throw him on the roof in frustration only a few times, but I found the experience intensely painful. It does get better, though, and after a few weeks they start smiling and laughing, and you can take them down from the roof, and everything's more or less smooth sailing from then on, at least until they become a Dreadful Teen and you have to get, like, a trebuchet or something to get them up there.