Paul Graham writes in his essay:
What you should fear, as a startup, is not the established players, but other startups you don’t know exist yet. They’re way more dangerous than Google because, like you, they’re cornered animals.
Looking just at existing competitors can give you a false sense of security. You should compete against what someone else could be doing, not just what you can see people doing. A corollary is that you shouldn’t relax just because you have no visible competitors yet. No matter what your idea, there’s someone else out there working on the same thing.
That’s the downside of it being easier to start a startup: more people are doing it.