Is the danger and exhilaration of it not part of the ‘buzz’ though? I personally wouldn’t be put off jumping into a lake or off a cliff into open water by any of this. I mean, you could just as easily have a heart attack going on a rollercoaster.
I’m not saying it doesn’t invariably happen, but it’s never, ever happened to me or any of the people I know, and we used to drink loads of cans and go pier jumping/jumping off waterfalls into rivers/lake swimming every weekend from spring onwards, even when it was really cold. Many of us still do well into our thirties, albeit not as often.