It is hard to go against expectations or popularity. But I would find it too challenging and restricting to only write about one topic. I love variety. I am small potatoes on Medium. But I get my biggest numbers (relatively speaking) writing humor and about Medium (no surprise.) But that doesn’t stop me from writing ficiton and some poetry. My Medium friends will just have to learn to expect variety from me. Like it or not. LOL!
I second your last statement. Be the writer you want to be.