I'm not sure why it's so easy to go ahead and do stuff that even one second's worth of thought would tell us is a terrible idea, but we can all confirm that it is. And anybody denying this is apparently blessed with a very bad memory of their own embarrassments.
So, if we can call ourselves good friends, it's our duty to reach out and give our buddies the warning that they're about to do something really dumb.
But sadly, none of these people apparently had that kind of friend around.