Margins.
Game development doesn’t pay more because game development companies can’t afford to pay more.
Sure, an individual game dev company may make a lot due to the hit driven nature of the field, but the totality of the market simply makes less money per developer than big tech does.
In order for that to change, the market has to increase in size by appealing to a more casual audience, or existing gamers have to pay more. Not something I think most gamers would like. And these are the people who the workforce of game developers form from.