The time i was there i lost count of the amount of people who came and went, seriously. Although i'm not sure how many other martial arts this applies to.
I observed it in three other styles, and I suspect it applies to every martial art worthy of the name -- that is, any style that's sticking to what it is, and isn't using gimmicks to retain students. Not making a value judgment here about who goes for it and who doesn't, but real martial arts will always be a minority taste. There's just too much repetition and too much practice, practice, practice. The average person nowadays doesn't want endless practice, and they want instant gratification and instant "mastery" which (okay, here's where I DO make a value judgment) probably explains the relative popularity of stuff like Guitar Hero vs. playing a real guitar, or a "martial arts" videogame vs. the real thing. Besides this, martial arts are time-consuming and not terribly convenient. In order to keep martial arts in your life, you have to be wired in a way that most people are just not wired nowadays.