Video game development is largely grunt work outside of the engine
This, and also, if you just take a step back and think of the bigger picture, the work isn't valuable. There's a lot more value in pushing ads, a CRM, an email app, etc than keeping a 14 year old kid entertained.
I don't really buy the supply/demand argument everyone else is saying here. The end product just doesn't provide value to people's lives. The amount of effort you'd need to put in to provide value in a video game is way higher than the effort you'd need to put into a productivity tool.