I think it is mostly just margins. Sure there are lots of people willing to work for no very little money for game dev but I would say there are tons of people willing to work for very little money for FAANG companies because they want that on their resume.

In fact since we are on hackernews that is kind of thing people wanting to be entrepreneurs do. Work at recognizable big tech company for a few years. Leave to be a founder of a startup. Investors ... well that guy came from google they must know what they are doing etc (the irony is they probably have less of the skills to start a company going that path).

They want it on their resume primarily to make more money and have a better career in terms of getting hired, etc. Very different motivation. They'd only work at a FAANG for free long enough to get that bump. Game devs however would work for many years underpaid because they like what they're creating.