"I'ts crazy that computer repair houses are still a thing."
I dont disagree with the gist of your post, but this is silly. Having a slightly older teen, I would say that neither he nor any of his friends disassembles PCs in any way. (They may be able to remove the cover and stare at it if it makes a weird noise, as most adults could too). I have obviously taught my son how to do it, but I think what a lot of people forget, is that we, the people who were there at the dawn of the computer age, had to fix everything ourselves. You pretty much couldn't own a computer without knowing how the damn thing worked and how to fix it when you broke it.
I really think that is missing from my sons life. He has the skills, I taught him. But he has no passion for the art of repair at all. His friends just never learned. So I think really its great that your son likes to do that and maybe i should have tried harder to get my son into it while he was still younger, but not everyone who had a mechanic as a dad grows up to be a mechanic.
Personally I think it skips a generation with some combination of genes and experience. My grandfather could build anything, but my dad takes his car to the dealership every single time.
But yeah, the good techs get picked up by a corporation sooner or later, or are the ones running their own businesses. I think actual computer stores would do better than an office supply store all around though. Repairs definitely lead to purchases in that situation. Its like taking your car to canadian tire as opposed to a real mechanic