> "grow my career by preparing for interviews in my free time" mindset

That must be sad life, is this common? I work as game programmer and me and almost every other game programmer I know code for fun, and we are not paid very well.

This attitude is why Game Development is such a terrible career. You get pennies for doing a difficult job under the guise of "yay fun" as though it is not a multi billion dollar business. You will be hard pressed to find a bigger mug than a mid level game developer. I remember working on the physics of Resistance at Sony for the PS3, and I was picking up 34 bags a year. Pretty much every other programming role I have had since is not only magnitudes easier, but pays way way more. It makes no sense to me at all.

Not that I would not accept higher salary, but I don't think it's pennies. It's way above average salary in general, and probably average in software industry. Not many game companies earn billions (except some outliers like GTA, COD, Minecraft, ...), average game company is on the verge of bankrupcy all the time. It's well worth it compared to a higher paid programmer whose job does not bring him happiness.

Well, it's a filter bubble. You can find enough people in both mindsets. It's mostly not related to pay -- related to job satisfaction, career growth options etc.