Sadly, many safety practices we now take for granted are the result of a tragedy.
After the Titanic, ships were required to carry enough lifeboats for everyone aboard.
The Andrea Doria carried enough lifeboats for everybody, but it sank sideways, making half of them useless. As a result, ships now carry twice as many lifeboats as they need, divided evenly along both sides.
The point is, we can't always predict every case, but the valuable lessons save many more lives.