If you want a successful challenge then you should avoid niches. Try doing what’s popular, for example a reaction video to some new movie clip or smth like that. That does require you to have an interesting personality though. Challenge videos, popular video games, and meme compilations are pretty solid for views.
I don’t suggest trying to get serious about YouTube. It’s tough, requires some amount of luck, a lot of amount of having just the right personality, is super competitive, and most of the time doesn’t pay off. I hate to say it but, why not get a real j**?