Well, yeah, this is a tough business. The fact is, there are hundreds of thousands of writers trying to break into the business every year. And there simply aren't that many slots. Then again, are all those writers and their work publishable? I highly doubt it.
If you just look at the number itself, the odds are not that great. But the fact is, unlike playing the lottery, not everyone has the same odds.
If you're a good writer and you've written a good story, the chances of you getting published is much better. Now you just have to work hard to get to that goal.
I think "acting" an apt comparison to the business of publishing (although they're different). I'm also an actor and have a tinny tiny bit of success, but I'd say that business is so much more brutal and not for the faint of heart. That doesn't stop aspiring actors from jumping into the fray every day, does it?
And really, just because the odds look so bad doesn't mean everyone has the same odds. Not everyone can be an actor -- the business is very realistic. It's all about skills, talent and looks. Right place at the right time, blah blah blah. Is it fair? Of course not. Some of the best actors don't get the kind of chances some no-talent starlets are getting. But real actors keep going. They keep going to auditions and getting rejections. Maybe 1 in 50 auditions would lend you a part, and maybe 1 in 50 parts will get you some attention and notice. Many of the world's best working actors have been doing it for decades. There's no "overnight" success.
So what do you do? You work your way through and be persistent. There's nothing more important than perseverance if you want to succeed in a business like acting or publishing. I've gone to numerous auditions and learned to brush aside all the rejections. And occasionally I get something, and I would work damn hard at it whether it's a good role or an extra. That's called professionalism.
But you really have to stop taking it all so personally. Persevere. In acting it's even more brutal. There would be 500 people at the open call and everyone seems to have the looks and skills and you feel crummy and you start to doubt yourself but you want to do your best anyway and maybe the casting director will see something in you. There's hope, but never a guarantee. You keep doing it. "Why not me?" you ask. And then there's a role you really, really, really, really want and you know you can do it well, and they give it to someone else. How is that fair? Well, it may not be, but you keep going. You don't give up. Real actors keep going.
At least in the land of publishing your book will always be yours. You're not trying to sell yourself (as in acting) but you're trying to sell a product -- so you can actually remove yourself from the emotions, if you wish. At least you're not criticized for being too short, too tall, too fat, too thin, too pretty, too ugly, or too ethnic. You can have 80, 100, 300 rejections and it still doesn't change the fact that your novel is still the same novel, and it only takes one agent or publisher to say yes. The flipside: No matter what you do, your novel will still be either good/brilliant or a piece of crap. No amount of submissions is going to change that. So you really need to look at your work objectively and see if it's the best it can be -- and if it's not, can you make it better or do you have another book?
You keep going if it really means that much to you. You don't give up. Real writers keep going.
Not everyone can be an actor -- it doesn't mean you can't keep trying. Not everyone can be a novelist either -- but it doesn't mean you can't keep trying. Just know what you're getting into and be persistent. And at one point realize whether you have what it takes or not.
Talking about the "odds" or how "it only takes one casting director/agent/publisher to say no..." is self-defeating. Why not say, "It only takes one casting director/agent/publisher to say yes"? I think that's more productive and you will feel better, too.
(And if you think I'm being condescending -- well, it comes with having 60 rejections for my first book and over 100 failed auditions to my name, and I still don't have an elephant hide.)