Multiple plumbing issues (broken toilet, clogged sink, etc). it has made me think that being a plumber is probably relatively lucrative, given how easy the most common fixes are.

My clothes dryer was recently shaking itself to death. Taking that apart was awkward, but in the end it was just a loose spring.

Most stuff is pretty easy when you get down to it. If something doesn't work, there is no harm in trying to fix it yourself. Worst case is you need to call someone, which is what you would have had to do anyway.