i would say that:

Bill did not think about the current picture of windows, when he started the project.

just start if you have a will and motivation and interest in this domain.

you will find your path!

It does not mean did you will be successful to build a complete OS, because the world is going complex and more complex there are number of people working on same thing but you will get indirect advantage that your knowledge increase, may be you got a good job on this, or something else