I write literary fiction. In the marketing world that means a 0.1% chance of ever being published. I am not in the zone of popular demand YET a book well written and submitted as a shining tribute to hard work still equates to a good read and worth buying. To polish and re-polish the work until it shines requires an editing process, a comprehensive context edit. That means money; big money. Self publishing is an alternative, but if the book has not been comprehensively edited; context, grammar, structure, character arcs...you name it, the lot, then it can only be but a glimmer of its potential.
So, I search for an agent to mentor, guide and encourage me to write and rewrite and polish that one book until it is ready for publication.