This post has come up on Reddit, and in the comments, a pilot discusses why he always wears his seat belt and some things he has seen.
In the responses, other pilots chime in, plus other people (like me) who have experienced a plane crash while on the ground.
I was also on a flight that suddenly dropped. Everyone I could see was seated and had their seat belts on, luckily, but one surprised gentleman accidentally threw his drink and some people had to hunt down their cell phones.
Have you ever been really glad you had your seat belt on during a flight?