The other day I had an interesting experience. For the sake of maintaining some semblance of dignity and not offending the person involved (although this individual is unlikely to be a computer user), I will offer an analogy rather than an actual account. Imagine that you are a firefighter. You fight fires all day, and you like it. At home you have a fire extinguisher in every room, you have family fire drills, and you certainly know not to throw water on a grease fire.
Now imagine that one day you are in your back yard, about to light your gas grill. Your neighbor, whom you invited over for a barbecue, informs you that the way you are lighting your gas grill is unsafe and could result in an explosion. And you look down and realize that he's right. How would that make you feel?