Why doesn't everyone know a lot about computers?

Not everyone knows a lot about computers because schools don't make it mandatory to know about computers in order to graduate. Furthermore, I don't think most computer-centric companies would appreciate the lack of profit should the public be able to be more self-sufficient with computers. In the United States, commercialism rules so only profitable ways, not necessarily self-sufficient ways, are possible (which is just one way unchallenged businesses will ruin the United States).

Because commercials show people doing the most extravagant gee-whiz things on computers which lead people to think they can do the same things, so they buy one...and there's no training mandated when buying one, nor competency demonstration needed.

Anyone with the money can buy one.

To them it's indistinguishable from magic.