Chris Keith offers an explanation. In general, I think he’s right. I would add just this: if you don’t write because you MUST write, don’t bother writing at all. If you MUST write, you know exactly what I mean. If you don’t, well you aren’t a writer so writing is just going to be a waste of time.
And second, if you send your stuff to one publisher and it gets rejected, send it to another. And another. And another. Some publishers are insightful and others are not. I once submitted an idea to a publisher and – because two of the people on the editorial board had a personal dislike for me (and that’s a fact)- the concept was rejected. By that publisher. In the meanwhile, the project got a green light elsewhere and is soon to appear.
So don’t allow rejection to become discouragement. If your stuff is good, it will appear. And even if you don’t get rich from it, so what. you MUST write, remember? The dissemination of solid work is its own best reward. Knowing that your stuff is being read is better than owning a porsche.