Carmack wasn't the only one behind ID (and therefore his own) success. Sure, he was the technical genius behind the game engines but he also was working with incredibly talented level designers, artists, and gameplay tweakers. Even other programmers like the legendary Michael Abrash. 'Hire the best...'
The other big part of their success was the direct marketing. Even if Doom was as successful as it was, they'd have made only 1/4 of the money if they used a traditional publisher.
Abrash books are very funny, they look like the thing you won't read in less than 2 weeks, and 48 hours later you're sweaty for not stopping reading. What a joy.
The other big part of their success was the direct marketing. Even if Doom was as successful as it was, they'd have made only 1/4 of the money if they used a traditional publisher.