There's the old joke about a plumber to charges $100 to fix a hot water heater by hitting it once with a hammer. The home owner, incensed by such a bill for a simple action, demands the plumber justify it. The breakdown is: $1 hammer strike, $99 choosing correct location.

Even a decade ago, the rewards for being able to repair computers were pretty substantial. Your computer was likely to have routine failures and you could probably save a lot of money doing piecemeal replacements. I think those things are still true for people who are trying to stay on the bleeding edge of computer hardware or use unusual setups, but for 95%+ of folks it is probably going to be a net loss.

For most people performing most tasks, they are better off taking the "one-screw" computer into the shop because it would take them hours and hours to do the research figuring out if it really is a "one-screw" problem. If you are wrong you could seriously damage your hardware. In addition, because hardware that is sufficient for most purposes and inexpensive is widely available - there is very limited utility in learning those skills otherwise.

If you want to learn about and repair computers as a hobby that's great! I do it and I enjoy it. But it's not a "smart financial decision."