some components fail more often than others, like caps or batteries, or are designed to, like fuses. sometimes it's obvious after looking even without measuring

I remember being out of work from my helpdesk job a couple decades ago and responding to a post on reddit asking for someone to help fix their PC. I went over and talked to the guy. He'd gone through three motherboards and was at his wits end because he couldn't get anything to turn on.

I looked over his setup, pulled out my pocket knife, stuck it in, and his PC booted right up. His PC case power button was broken, so I jumped the pins to make sure it was just a mechanical issue. Then I wired his reset button up to it instead. He gave me his old Dreamcast on top of the agreed upon six pack because he was so relieved. It was great for my self-confidence while I was out of work.

TBF, the switch is a mechanical part that goes through a series of stresses, not just from the person actuating it, but also from the electrical forces causing the switch to bounce and arc for several ms before it settles. Putting all that stress into a little package with tiny contact wafers, and it's bound to fail sooner or later.

My family has always liked working on things that are broke - what can go wrong, you were going to throw it anyway and sometimes you can fix it. If you can't fix it a vacuum in parts fits in the trash better than it put together, and sometimes you get a working vacuum. (the implication here is you don't put it together unless you think it will work)