"Don't try to guess what sort of thing editors want to publish or what you think the country is in a mood to read. Editors and readers don’t know what they want to read until they read it. Besides, they're always looking for something new." WILLIAM ZINSSER
It's scarier to trust yourself. And write the book that's in you to write. The book that only you can write. It's risky.
But which is riskier?
To follow the trend? (By the time your book comes out they'll have moved on to something else.)
To try and write the book that that someone else writes? (Won't they do a much better job at being them?)
Or to write the book that only you can write? And possibly find yourself ahead of the trend, setting the trends, doing something startling and new?