Hot Open 120v wire found in attic. Do you have a switch that may kill you?

I was looking for pendant boxes and wire and just stuck my hand down in a pile of insulation and found a hot wire just buried there. Other points on a newer house about the junk builder grade water valves, Why it's important to look in your breaker box for neatness and you may have GFCI built in there that you need to know are there.