I often find myself thinking about this. I talk to less people in person about music than when I was in high school or college and the world has obviously shifted to being more and more online. So, especially with newer artists, until/unless I see them in concert, I have no idea who an fanbase is, outside of faceless interneters like yourselves.

So seriously or humorously engage with me on this.
List an artist, and we'll tell you who their fanbase is.