I've been in a situation where we were administering CPR to someone who simply could not have been helped by CPR (although there was no way of us knowing that a

I've been in a situation where we were administering CPR to someone who simply could not have been helped by CPR (although there was no way of us knowing that at the time). We were relieved by first responders in about 3 minutes from calling 911 though. Plus, as others have said, it's also beneficial for the bystanders to be doing something beneficial. In my own situation, I didn't know for sure that CPR wouldn't have helped until the autopsy came back. That's a pretty big time frame to sit around and wonder if you could have done anything or not. If you're just a random person on the street, you may never get that information to ease your mind.