Today the most popular shounen mangas are One Piece, Naruto and Bleach, right?
But a few years ago, it used to be DragonBall, Yuyu Hakusho and Slam Dunk. And at the time the WSJ was much more popular than it is right now.
Besides, the YYH anime was almost as popular as DBZ and had ratings at the time that were bigger than those that One Piece (the shounen anime with the biggest audience) have today.
There are other rich mangakas. The woman that created Ranma is the richest woman in Japan, isn't she?