From the outside it can look like you’re in competition with other authors, but I don’t feel that way. And I don’t think it’s useful to look at other authors as competition, even if they write within your genre.
You can argue that when someone decides to buy a book, they could buy someone else’s book instead of yours, and therefore you’re in direct competition with other writers. But that is just a temporary restriction; a reader may not buy your book that time, but they may buy it at another occasion. And the more people read and buy books, the better it is for all writers because the audience gets bigger.
Most people don’t read books
The number of readers is relatively low. I think a lot of people prefer to watch TV or movies instead of reading a book because it requires more mental engagement. So to me writing has always been about getting more people to read in general, not stealing away readers from other authors. If more people read, then more books will be read by more authors. If a new reader discovers a good book, they may be inclined to read more books by the same author, or read similar books in the same genre by other authors. So you can only win.
Those that do, read lots of books
Most of those that read regularly, read lots of books. Some genres are dominated by a handful of authors, but that doesn’t mean there is no room for you. On the contrary! Sure, most readers have their favorite authors. But that doesn’t mean they won’t ever read anything written by other authors, especially if their favorite author is still working on a sequel or taking some time off. It’s like having a favorite TV show; you will not watch that show exclusively and nothing else ever until you die. You will want to try out other things in the same genre or something completely different, either to wait until the next season comes out, or to mix it up. So once again, you can only win.
And there is also another huge upside; once a book series has ended, those readers will look for the next great series to read and that may be yours. Why then waste your time being bitchy at other authors?
If authors help each other out, and promote newcomers and other authors (even established ones) they really like, it will benefit everyone. You interact with your audience, the readers get to know another author, the other author will be grateful (and may return the favor when he/she is the big shot!) and you create a positive atmosphere for everyone.
For me the author’s community is like a company; there is no point in fighting within our midst since we’re all selling the same product. It’s about working together and promoting the creative writing space as a whole in all its genres, from comic books to poems and everything in between. It doesn’t mean you have to be loyal and defend absolutely everyone. There are “authors” that I don’t think are worthy of that title, but ultimately the readers will decide who they support and buy books from, and as I said above there is no point in tearing each other down. Best case scenario you start a feud with a fellow author and you both lose respect from the audience (because newsflash, everyone can publish a book.). So don’t waste your time on being negative and judgmental, take that energy and do something positive.