In today’s world, many writers start by writing fanfiction. For those who don’t know, fanfiction is original work based on/inspired by existing properties. It is amateur work (although one could make the argument that the expanded universe of something like Star Wars is simply professional fanfiction), written by fans for fans. On the surface, there is no merit to it. Authors will never be paid for their work. That said, it can be a value learning tool. A free workshop in a sense.
I wrote a lengthy fanfiction story for Avatar: the Last Airbender and I will attest to the value in what was a tremendous learning experience.