Few of them actually make a fortune.
Carmack hit the jackpot because he was one of the founder and top shareholder of ID Software when Doom 2 and Quake were so successfull...
In the end those that make money are those who own a portion of the studio they work at and hit the jackpot when that studio is bought by another company....
Otherwise most studios can't afford to pay millions dollars salaries so the cash thay make is through stock options.
Miyamoto probably is very wealthy thanks to the nice ride the Nintendo stock had these last few years.
Pardo at Blizzard probably has a nice bank account too as these last years Blizzard has been awarding a lot of stock options and I bet he got a nice share of those...
PS3-Xbox360 gap : 1.5 millions and going up in PS3 favor !
PS3-Wii gap : 20 millions and going down !
