If you've read the fairy tales, then you might understand the danger of comparing yourself to others. Remember that wicked queen in Snow White? She could have been a happy person if she had just quit asking that mirror who was the most beautiful of them all. I mean, really. People do get older. What did she expect?
Of course, you probably aren't one of those people who talk to mirrors and expect to get answers. And you may even have become resigned to the fact that eventually, you're going to see a few wrinkles here and there. But when it comes to your writing, what then? Do you glare at your hazy reflection on your laptop screen and ask, "Why did that writer get a book deal while I've been slaving away for six years with nothing? What's better about his writing?"
Actually, there might not be anything better about his writing, but you just fell into the trap of comparison. It's a dark hole, and no writer will ever find success in it.
The truth is, there are a myriad of reasons why any one editor or agent accepts a manuscript on any given day. Sure, you've educated yourself so that you aren't the goofball who sends fiction picture books to houses that publish adult nonfiction self-help. Yes, you've honed your craft so that you don't send in faulty work, hoping professionals will ignore your horrendous plots, shallow characters, or unrealistic dialogue. And you rewrite and run it past our critique group until it's as perfect as you can make it.
But sometimes, it isn't that your work is poor. Sometimes it's just not what that one person who is slogging through the slush pile is looking for. And sometimes, someone else's work is. That's okay. It's part of the way publishing works. If you're producing good work, someday you'll be the one freed from the slush.
So take a lesson from Snow White and avoid comparison. Enjoy the success of your writing comrades, but focus on your writing. Take heart. Your writing is as unique to you as your own finger prints. Some people will like it, and some won't, but it's born out of who you are. That's just the way it should be and the way it will be if you don't give up.