Niche is not a costume
People mix this up. Your personality is how you talk. Your niche is the job your content does for a specific person. "I am funny" is a personality. "I teach new streamers how to sound clear on a cheap mic" is a niche.
Broad topics feel safer because you never run out of ideas. They also make you interchangeable. Narrow topics feel scary because you can see the edge of the audience. That edge is where people remember you.