I've had many jobs, more than most people I suspect. A partial list would include: bus girl, dishwasher, cook's helper, bartender, waitress, nursing assistant, clown, research assistant (on projects from viruses in ducks to follicle size in horses), flower seller, pre-school teacher, nanny, house cleaner, science teacher, business owner, primary school teacher...and the list continues. So I have a good idea about the ups and downs of most jobs. I've been a writer now for ten years and I can tell you unequivocally that writing is a tough gig.
First you have the writing itself. Trying to get that wonderful image in your head down on paper. It's never good enough. It needs re-writes and re-writes. Even once it's published you still want to get in there with the red pen. You always feel like you've failed the story in some way.
And then there are the gatekeepers. There are agents, editors, and publishers all standing ready to reject your work. And the rejection is based on all sorts of things you have no control over. Sometimes as simple as the person is just not keen on that type of story. The writing might be good, there might be a market but that particular person just doesn't like that type of story.
And then let's say you get published. Now you have the reviewers. All coming with their own histories and prejudices. Some untrained. Some with axes to grind.
After you've got through all of that, then you get your royalty statement. If there was ever a document that can destroy a person, a royalty statement is indeed one of them. A year of selling and your publisher has managed to sell 9 books, or worse 1. Yes, I've had royalty statements like that. And again, the royalty statement, the sales for your book, have little to do with how good the writing is. I have books that have sold in the 10,000's that are not as good as some that have sold in their 10's. It's about the market and probably more importantly, the marketing. If your publisher is not pushing your book, you won't make money, no matter how good the writing is.
The thing about writing that is so hard is that so much about your success has nothing to do with your writing. This can be frustrating. I'm used to jobs where if I put in my maximum effort I expect to do well. Writing doesn't work like that. Despite what anyone tells you, a lot is about luck. About things you can't control. It's a really tough job and you'll be bashing your head against a wall if you don't accept this early on.
So why do it?
I do it because I like it. I do it because it is one job that will never bore me because I will never reach my maximum potential. Each story I write pushes me closer and with each story I write the line that's marking my maximum potential moves that bit further. I like that. The other things, the ones I can't control, I've tried to make a problematic peace with.