You're missing a big factor: money. It takes significant capital to start your own studio. In games, only the founders are making real cash, and only if they're actually successful the first time around. Programmers make significantly less than they do in other fields, for example.

And then in terms of reputation, very few people in games - usually designers - are household names. I'm talking maybe a dozen or two people in the entire industry (vs hundreds in film). And I would assume that it's very hard to get outside investment without that star power.

Finally, games is an enormously crowded space. Thanks in part to the massive influx of indies, improvement in tools, etc there's an insane amount of oversaturation on platforms like Steam. This means that thousands of high-quality games go completely unnoticed and die a quiet death. Unless you have that star power to get people paying attention in the first place, or you win the social media lottery and go viral, you're probably toast.

So yes, the market is huge and growing, but despite that it remains a really brutal industry to be in. Big studios know this, and they take full advantage of it, knowing that their employees would likely have it even worse if they left.