Your argument (like so many others on this forume) is reductio ad absurdum. You can google that, or pick up a dictionary while you're getting your bubble wrap.
As has been mentioned the dragon boat mishap is more an error in judgement, lack of skill or just pure negligence on the part of the coach/captain/steersperson and less an issue of wearing a lifejacket.
The wearing of a lifejacket is a passive preventive action.
Common sense, steering skill, etc., these are active preventive actions that were left on the dock.