"How to be a top YouTuber" by MrBeast. "How to be a top athlete" by C. Ronaldo. "How to become a popstar" by Ed Sheeran. You know that such advice will have limited usefulness to most of the aspiring people.

Karpathy is an exceptional person, maybe not as much as Ronaldo in football but taking advice from him similarly won't be guaranteed to work. You can't have guarantees in such things.

In truth, the more literal but not fully literal thing that happens regarding surviving a PhD is that you try to publish a paper in a top venue but after several rejections you publish in a lower tier one, then you do two more followup in similarly second tier but not terrible venues and you get a "magna cum laude" or perhaps a "cum laude" once you reach 5 years and the prof wants to avoid the embarrassment of not having graduated you.

Of course many people don't come into the PhD with such plans, they expect a summa cum laude and papers in top venues and talk invitations and so on, since they've always been a top student so far.