I think it depends on the person, and also the circumstances. For me, definitely not the hardest job (of the many hats I wear) I have. It’s the most fun, but rarely hard work. Long hours, yes—sometimes thankless, but more often great fun and immensely rewarding.
I know a mom who has three children, two of whom have major medical issues. Her life is filled with pediatric hospital stays and some pretty advanced home-medical care—and balancing that with trying to meet the kids’ needs and giving them a good childhood is a constant challenge for her. I see her bearing up under the pressure with great grace…but I know there are times when she must just weep with exhaustion and frustration.
As for the rest of us – who have won the lottery of having relatively healthy children, just like other jobs—some people are more talented or better equipped to do their job than others.
And, in the same way I’ve met some incredibly inept waiters or outrageously rude “customer service” folks.. I’ve certainly met people who should never have had children – they are horrible parents and they seem miserable and so are their kids. I’ve heard those people whine (I’m thinking specifically of a stay-at-home mom I know who lays on the couch all-day and doesn’t do a thing for her kids) about how HARD it is to be a mom… and I just want to dope-slap them.
If you aren’t having fun, you might be doing something wrong. If you haven’t parented appropriately from the get-go (with boundaries, consistent discipline, rewarding good behavior, setting expectations, lavishing your children with love) and you wonder why your kid hits/bites/curses and can’t make friends… well, perhaps it IS a hard job being a parent if you aren’t suited for the job at all.