The important part of any writer who doesn’t just write for himself or herself is finding an audience. It doesn’t have to be a huge audience. You don’t have to try to sell your book to everyone. However, you will need to try to get a sense of who you are writing for in the planning stages of the book.
There is a lot of value in trying to succeed within a niche. It is always easier to be a big fish in a small pond than a big fish in a big pond, and that goes for all fields. However, if you make the pond too small, you’re going to create something that few people will like. It is possible to find an audience for almost everything on the Internet. However, it’s often challenging to aim at a really narrow target, especially since getting the attention of anyone online is often hard in the first place.
Still, people might underestimate the amount of room available in popular niches. You might think that there are too many books in a particular genre and that you’re better off writing something in a topic that few people explore. However, popular genres are popular for a reason, and unpopular genres won’t necessarily become popular just because the popular genres are too huge.
In many cases, this is a situation where the rich get richer and the poor get poorer. People have been complaining about the lack of originality in romance stories for a long time, and the same goes for a lot of action epics. It doesn’t stop writers from continually churning out popular works in both genres over and over again. The critics who complain about the overexposure of something will rarely actually stop it from getting exposed some more.
At the end of the day, it isn’t the genre that determines the popularity of a book. It’s the marketing. It’s possible to turn stories that are bizarre into huge hits as long as they are marketed correctly. Stories that are too bizarre to be huge hits can still be small hits when aimed at the right audience. People who can use social media, Reddit, and many of the other resources of the Internet to find the right audience will be the people who succeed. Whether they write something that a few hundred people will love or something that millions of people will quote, it’s because they marketed it correctly.