Was on a remote beach by the RCA towers in California, in a time before cell phones, on the first sunny weekend in April after a storm. Was watching someone hang-glide, while the guy was trying to land on the beach. Because I was watching and knew something about gliding trajectory, I could predict the hang glider was going to touch down crotch-deep in the surf. Not good. Because nobody else seemed to be watching, I got up and ran all the way down the (naked) beach to help out before the guy landed. Before I arrived, the guy was immediately pulled out by 6-7 ft waves. Couldn't figure out how to unwrap the guy from the lines when he would pop up, so I had to swim away, knowing that he could get caught underwater as he was pulled further out by the high surf and his glider maybe got hung up on the nearby reef.
When I was out in the high surf after freeing the hang glider's hands, I looked back at the nine people lined up on the beach watching us. If at that point I had thought about what this experience was going to mean to me, if I had personally known the hang glider, if I had reacted with outrage at those nine observers, I might have drowned. My ethics had been (up until that point) to help without thought to my own needs. At the time, I realized that I was out far enough off shore in heavy & rough, cold surf without a way to cut the guy free from his glider. Saving myself was now the new priority, so there were not two people drowning. So I swam away.
The nine others watching imagined I must have known the guy. They concluded the only reason I swam away was that I didn't have a knife. So they sent their best swimmer who knew life-saving techniques out - with a knife. Once I stumbled onto shore, my admonition that this was not the movies and just one person doesn't have to be The Hero, everyone else who could swim jumped into the water to help out too.
The hang glider guy was saved from drowning. Standing there looking at him as a wet cocoon by the fire people were building to warm him up, I realized how often I had tried to save people I loved in my own life, and how close I was to being pulled under in those situations too. It had profoundly affected me to turn around on that hang glider, knowing that I could do nothing more about saving him. It was quite a gift for me to know the real boundary between saving someone else and saving myself.
Fortunately, I didn't have to pay with regret that my "life-lesson" had resulted in a death. If I had not jumped in, the trained life-saver wouldn't have thought to ask among others on the beach for a knife.
I never did find out the hang glider's name. I just walked home down the beach, exhausted and happy that he was alive.