I know video essays on YouTube performs really well. Especially if you're not repeating yourself 20x just to get one point across. But you'll hit an end where you won't have much to talk about that people would really care about.
You could write fanfictions, something I recommend is reading other people's fanfictions first to get a feel of what everyone is writing and write something different. If the story gains popularity you can change names and settings to make it an original story.
Another thing you could do is expand from DBZ and use those knowledge to write your very own story. You can even create a game inspired by it with some friends or siblings. If you have any.
Though I do want to say that whatever you do, money isn't a guarantee. Projects flop and that's okay, you have to be willing to lose in order to gain. It's just a journey to a goal. Goals are ideal, journeys is the present and you want to gain experience from the journey as much as possible.
