If "everything from scratch" means truly everything, well, that's a nice thing, but pretty dangerous in some ways. What I mean is that being a top-class low-level coder means you'll be able to ace most programs in terms of speed, but it also means your knowledge will be very limited, chained to a specific hardware/OS combination. Like how VGA graphics in DOS was insanely simple, but in OpenGL, even that became a bit problematic. Freaking slow, too, but at least it worked in WinXP.
But, you could always just lucky and guess who'll come out as a victor from the next-gen console war, and master that architechture.