[Dessesaf]

The really challenging part when you're building an OS comes from not building an incrementally bigger and bigger mess until you're stuck and can't make any progress any more.

You're right, there's no magic here. It's just lots and lots of work. And there are important decisions to be made about how you design and abstract everything. None of them are hard, but making so many decisions is the very thing that's hard about most programming.

The answer of course is to have lots of programming experience. Which is why building an actual OS to the level of SerenityOS is not something a reasonably skilled graduate would be able to do.