If you can't build something yourself, then you won't know how it works and what the consequences of the relevant design decisions are. I do it because my goal is to learn how to do things right, not to get things done quickly.
That's cool, and I indeed like to understand things too, but how do you deliver anything of value to a business if you start of designing a CPU? ;)
CPU? Your jumping all the vital underpinnings. What if the copper was of low quality or the silicon was a low grade? I'm in a cave rubbing sticks together to make fire.
What an absurdly high level of abstraction to begin with.
First, I create the universe.
Do you know how that sentence you wrote right there works? Did you create the English language?