This article is 2 years old, but it probably still applies.
tl;dr
- It's harder to get into than actual programming jobs at a game studio because not every studio hires a dedicated writer and typically outsources writers
- It's hard to gauge the quality of a "video game writer" due to the subjectivity of writing, and therefore harder to get into the industry as a writer
- It's a collaborative effort; you could write a beautiful script for a moment in the game, but said moment could be cut due to time constraints
- In relation to the previous point, just because you want to write something doesn't mean the designers are going to design something around your script
- You will almost never write a script from the ground up; by and large, writers are hired to flesh out stories already created
Basically, it's almost not worth the effort if you enjoy creating original stories.
EDIT: This just reminded me. I took a Coursera course you may or may not appreciate.
Transmedia IP was a course I took where you write a few chapters of a novel, adapt those chapters into a screenplay, then adapt it into a video game. I got a full-time job once I got to the video game part and never finished (breaks my heart, because I love me some video games), but I imagine that would be something you could benefit from.