Publishing has nothing to do with writing. Not getting a yes doesn’t mean it isn’t good. It could be the best thing you’ll ever write (in a good way) and still not get an agent or publisher. No one would have known about THE MARTIAN if Andy Weir hadn’t published it himself, attracted tons of readers, and *then* attracted the exalted industry because they saw it was already doing well. Readers know what they want. Publishers and agents have to guess on their behalf, and they can often be wrong.