Bottom line. It's not just what you write but who promotes what you write. Period. If it has the publisher with shelf space clout, the "face" or "name," and/or maybe the topic of the moment for which the public calls, there is a chance.
However, there are many authors who continue to write books that have smaller sales, but consistently have a following. That market grows over time sufficiently that several books in print may produce a reasonable career. Some, like lottery winners, hit a winner that gets the spokesperson, the sponsor or even the movie.
Talent abounds everywhere, on street corners and in churches, in book stores and in school choirs and bands and athletic fields. Recognition of that talent is dependent on many factors. Again, sponsorship of one form or another is critical. For authors, that seems to be the established leaders in the publishing world.