There is obviously nothing wrong with just sticking to a single genre, but it does depend on what you want out of reading.

Personally, I read quite a lot. We're talking 200+ books a year, so forcing myself to sit through a genre I'm not that excited for isn't "that big of a deal". But if you're only reading 20 books a year, suffering through a single book doesn't seem worth it to me.

I mainly read fantasy and sci-fi, and the r/fantasy subreddit does a yearly book bingo. I joined them two bingos ago, and since the goal of the bingo is to widen your taste, and try out new genres or niches, or themes, or specific authors, it was a very nice stepping stone to trying out new things.

But yes, we're on the third year of experimenting with different genres and I've learned a lot and it has been an enjoyable journey. But it is definitely challenging, and a little bit of a money waster because I keep buying books (tho often on sales) and then dropping them because I have NO interest in reading them.

That is important, drop books that don't fit you. But if you're on the "ehh" or the "meh" or the "whatever" stage, try to push through. Because a single book in a specific genre doesn't mean the entire genre isn't for you.