[Electronics] How is this simple circuit life Threatening?

Today I take a look at Gk Invents 240 to 24 converter circuit - what could go wrong? https://youtu.be/0hPLn48qYX8 After years in the electronics industry repairing and testing radio transcievers, test and measuring gear. Time to put that experience to revewing practices that are life threatening if you are a young player.