"Designing an OS is like creating your own world"
Making video game is also like creating your own world!
And it's order of magnitude less hard than making an OS...
Bonus point, you have a chance to make a living from it!
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.