Vanity Plates and Mad Gab

While driving on the Parkway yesterday, I was behind a silverish gray mazda 3 whose license plate read "cestl- vi." After reading it aloud to myself a few times in different combinations I exclaimed, "c'est la vie!" Haha! I had figured it out.

I ordinarily don't find mad-gab very fun or deciphering peoples' convoluted plates, but this was an exception.

Vanity plates are a strange concept to me. Are people just trying to come up with something creative to fit in the 7 slotted space? Is it so that when you get in an accident, you don't have to look at your car or registration, but instead just know it? I mean, they are called "vanity" plates after all! So are they for vain people?

Someone set me straight please.