Why is learning about computers so hard? Well I think complexity is one of the main problems among some others. The speed at which one technology has been replaced by another that fufills the same task also adds to the work. To really understand computers I think you have to have an Idea of how to go all the way from the top to the bottom, or bottom to top.
Computer understanding from most abstract to least abstract
-The Internet
-Operating systems
-Programming, ie python --> c --> asm --> machine code
-Basic Electrical engineering stuff, v = ir, caps, inductors, etc
-Integrated circuit design + digital logic
A good question would be, where should you start? Top to bottom? Bottom to top? Some of both?
If you start at the bottom you will learn good fundamental things but it'll take a while to get anywhere if you just want a job or money asap. I think learning math from the axioms would be fun, but my guess is that it'll take a while to get to like calculus for example.
Maybe a good idea is just to jump in wherever you think is interesting. I'm certainly not an expert in any of these areas, although I'm working on it. It's also probobly a good idea if you seem confused to get an old computer. Linus torvals started with a VIC-20 as his first computer and said in a talk titled "The Origins Of linux" in 2001 that if he started today he could not understand the machines that we start with today. 25 years ago the creator of linux believed modern computers were too complex for a beginner to just understand. Maybe it's a good idea to get an old computer, although I think the development of a simple computer with display and keyboard, something like the Commodore 64 or apple 2 with some simple languages built in would be good but built with common microcontroller chips, just so you don't have to deal with 40 year old machines designed to last 5 years.
I think it's also helpful to learn about the history of computers. MIT press has a short book on the history of computing which is ok, understanding how we got to transistors I think is important. mechanical -- > relays --> vaccum tubes --> bjt --> mosfets
I think that layout is right
I've seen some stuff on optical computing. Quantum computing is also interesting, but I don't know all too much on it, and it might be useful to know if they become more prevalent.
It might also be helpful to know that each of these subjects may seem fractal like with many areas to explore
This is ok, you probobly won't learn it all but I think about it like this: Do you need to read every service manual of every car to be said to "understand" cars? No, once you understand how one car works ie internal combustion to transmission to wheels, etc, you can graft that knowledge onto other cars. Some cars may be more different than others, and that's ok. However, as a newcomer it may seem very daunting when you can't tell what the landscape is.