I'm gonna be straightforward. If your goal as a content creator is to start a channel just for the sake of making money you're already starting wrong.
Like most, I too started a channel with the sole purpose of monetizing. I got drawn into the idea that all these YouTubers were making videos and making money so easily. They would get sponsors who gave them stuff, companies giving them products to try out and make videos of. Then I learned it's not really how it all works. I learned YouTube has millions and millions of ppl joining every day, uploading millions and millions of videos every day making it almost impossible for me to stand out and thus likely not be able to profit from it. At least not at first.
I can understand where you're coming from but this is not the way to go. If you're looking for a niche to make money it means you don't have a niche you already enjoy. Most ppl who become YouTubers tend to make content based on what they like or what they are good at. For example, I'm a gamer and I'm a techy person. Both these niches would be right for me. But I couldn't go into beauty (a very popular and monetizable niche) or sports (another big niche) because I am neither into beauty nor am good at all in sports of any kind. Even if these niches were big money makers I just wouldn't be able to create content for either.
You need to find a niche that's best suited for you and make it work for you. Picking a niche just to make money will be a journey that will likely end in failure or will take an extremely long time to reach your goal unless it happens to be a niche you're good at.
That's my take. Take this advice as you see fit.