I hope he learned something useful while doing it and it seems like he did, because, although regarding all the comments here I'll likely be alone in my assessment, I just see a massive waste of time & effort? He described it as "a brutal year-long journey of 18 hour days" and he didn't bootstrap a company, he wrote Doom in Typescript types...?! The "epic" doom music underlying his story just makes it seem even more comical to me.
Maybe it's just me, don't want to crash the party. Carry on