How do people learn to make computers?

I see all these people creating new various computers just like the guy in which made this cheap a single at raspberrypi as well as stuff that way and I am just curious how may you learn to try and do that We’ve recommended and can be done with things already availible within current engineering but how do you learn to generate them

Hee hee..i prefer the tiddly pi computer system.
You should study electronics captive market and pc science to generate that.
Its not like building a desktop pc, using instant components.
They designed the signal and chose the component valuations and produced the pcb.
Which requires several education.