actually making a video game would be 100x more complicated. Plus kernel developer jobs are more lucrative than most game dev jobs.
Is it really more complicated to make a video game that a kernel?
I don't consider myself knowledgeable enough to make a full kernel by myself but I did manage to make a full 3d video game by myself.
Also I'm not speaking about making a game engine along with the game.
Having a kernel dev job is different than making your own kernel, speaking on a "world builder" perspective.
Even a 3D game engine can be simpler than a fairly complex operating system.