There are also different styles of teaching and learning. Karpathy always like to start from first principles and increment the building blocks.

Whereas for example Jeremy Howard's style resonates a lot more with how I enjoy learning, very much a "let's build it" and then tinker around to gain intuition on how things inside the box are working.

I see the benefit in both approaches and perhaps Karpathy is more methodical and robust. But I just find Howard's top-down style a lot easier to stay motivated with when I am learning on my own time.