Akira Toriyama's Dragon Ball manga and subsequent anime series is considered a major cornerstone of shōnen entertainment. The series' later debut on Toonami in 1998 was a gateway for a whole generation of anime fans.

Apparently that is no longer the case in Japan, where while Dragon Ball Super is currently airing, the manga ended over 20 years ago. My Navi Student polled 403 college students, both men and women, on whether they ever read Dragon Ball . Shockingly, only 64 answered that they had (15.9%). The other 339 people (84.1%) said no.

It appears the generation that read the manga didn't pass on the series to their offspring. Those who had read it, did so either because of the manga's reputation, they borrowed it from their boyfriend in junior high, it was readily available at the school library (or in one case, at a hair stylist) or their friends were reading it. Others started with the anime and then went back to read the manga afterwards.

Many who hadn't read it stated it was because the series was too long at 42 volumes, it seems dated, or they found the anime fulfilling enough.

Source: Mixi News via Yara-On!