Because they like secretly jerking off over everyone talking about it. It's not much different than the kid in the school that pulls the fire alarm and runs away, etc.
Also not saying it is true in this case but I think sometimes the leaking of rumors is intentional.
For example there is an ice cream/junk food bar in Fitchburg called Carol's. Every year someone will start a rumor on faceplant that "Carol's is closing" and every year it ends up being false. I'm beginning to think that someone just does it to be a jerk or its some employee at the restaurant that does it to drum up interest in the establishment.
-Mike