How many Walkman's or Discman's did you buy before the iPod came out? The market for portable music devices went up exponentially from the 90's to the mid-2000's when the iPod achieved mainstream status. I bought two iPods in three years before the iPhone made 'em useless.

Consumer behavior isn't set in stone.

Source: http://www.in-stat.com/press.asp?ID=1366&sku=IN0502148ID