How is it a harmless prank if at the end the ‘prankster’ walks away smugly and the salesperson is left with a broken demo? It’s only harmless if the prankster

How is it a harmless prank if at the end the ‘prankster’ walks away smugly and the salesperson is left with a broken demo? It’s only harmless if the prankster turns around and fixes the demo. I remember some years ago there were people going around trade shows with universal remote controls turning off the screens. As far as I remember most posters thought that wasn’t a very nice thing to do. And that really is almost completely harmless.