This is because Carmack doesn't really do OSS, he just does code dumps and tacks on a license ("a gift"). That's of course great and awesome and super nice, but he's not been painstakingly and thanklessly maintaining some key linux component for the last 20 years or something like that. It's an entirely different thing; he made a thing, sold it, and then when he couldn't sell more of it, gave it away. That's nice! Bu…
He also (presumably) doesn't have to worry as much about money as many OSS folks might, so dual licensing (as a means to keep working on the OSS version while also making ends meet) is likely not something he would consider. He also started an AI company, right?
Yes, but IIRC it's different than the current "download the internet" large language model approach. More like learning to play video games or something.