John Carmack on what he admires about Elon Musk

December 17, 2025

Programming legend John Carmack is asked about his relationship with Elon Musk, to which he replies:

“In some ways we have a similar background. We’re almost exactly the same age, have backgrounds programming personal computers, and have even read similar books that have turned us into the people we are today.”

John first met Elon when he was building Armadillo Aerospace. Elon visited Armadillo with his right-hand propulsion guy, and the three of them talked about rockets.

“I think in many corners [Elon] does not get the respect he should for being a wealthy person who could just retire,” John says. “He went all-in, and he could’ve gone bust. There’s plenty of athletes or entertainers who had all the money in the world and blew it. [Elon] could’ve been the business case example of that with the things he was doing: space exploration, electrification of transportation, and Solar City type things. These are big, world-level things. And I have a great deal of admiration that he was willing to throw himself so completely into that.”

John contrasts this with the way he approached his own aerospace company:

“I was doing Armadillo Aerospace in this tightly-bounded way. It was ‘John’s crazy money’ at the time that had a finite limit on it. It was never going to impact me or my family if it completely failed, and I was still hedging my bets working at id Software at a time when [Elon] had been really all-in. I have a huge amount of respect for that.”

It also irritates John when people call Elon “just a business guy”:

“Elon was deeply involved in a lot of the [technical] decisions. Not all of them were perfect, but he cared very much about engine material selection and propellant selection. For years he’d be telling me to ‘Get off that hydrogen peroxide stuff. Liquid oxygen is the only proper oxidizer for this.’ And the times that I’ve gone through the factories with him, we talked about very detailed things like how this weld is made or how this subassembly goes together. He’s really in there a very detailed level . . . I worry a lot that he’s stretched too thin. He’s got the Boring Company and Neuralink and Twitter too whereas I know I have limits on how much I can pay attention to.”

John continues:

“I look back at my aerospace side of things, and I’m like, ‘I did not go all-in on that.’ I did not commit myself at a level that it would’ve taken to be successful there. And it’s a weird thing having a discussion with him. He’s the richest man in the world right now, but he operates on a level that is still very much in my wheelhouse on the technical side of things.”