I strongly suspect the reason he can work so much is that he only works on things he finds interesting and doesn't have to answer to anybody. He doesn't have t

I strongly suspect the reason he can work so much is that he only works on things he finds interesting and doesn't have to answer to anybody. He doesn't have to take calls and random meetings in the middle of the day. He doesn't have to work on boring parts of a project. In fact he is known to completely isolate himself from the project and not really communicate at all for long stretches of time. If you look into the Doom3 codebase you will see that the engine is written in C++ while the renderer is written in C. Carmack worked only on the renderer. He didn't even talk to the rest of the team to use the same programming language. They later retrofitted the C renderer to work with the rest of the C++ codebase. Think about it? In the situation where you pick the part of the project you work on, you choose the tools, you choose the programming language, the computer that you work on, your own hours, your own arbitrary deadlines which you can ignore without much consequence, you can ignore meetings with everybody else and have the meetings on your own terms if needed, would't you also be more productive, happy, and more motivated to work longer hours? Also, you take home millions and millions in profits as you are the owner of the business.