The problem is when you go back and forth between trying if it worked, turning power on and off again, and at some point you become sloppy and forget that you d

The problem is when you go back and forth between trying if it worked, turning power on and off again, and at some point you become sloppy and forget that you didn't turn it off. I've electroshocked myself twice while working on appliances (not PCs). After going back and forth a few times I thought I had turned off the circuit breaker (which also has a vibrant red strip to show that it's hot) but I didn't and touched the live wire. If you look at safety guidelines for electricians, they require people to have multiple safeguards in place so that a single mistake doesn't kill you. That being said, household voltages probably won't kill you and some people open PC cases while they are running, so there's that. As long as you're not messing with the power supply I don't think PCs are really that dangerous.