“Tippler” means “drunkard,” and he inhabits the third planet that the prince visits. The little prince feels really sorry for the tippler because he looks so dejected. The tippler turns out to be as silly as most grown-ups and explains with convoluted logic that he drinks to forget his shame, and that he is ashamed because he drinks. In this vicious cycle, he’s never able to get anywhere: he’s always drinking, and always miserable.
The prince spends as little time with the tippler as possible. Even then, he still ends up feeling “deject[ed]” (12.1) and “puzzled” (12.11). The tippler emphasizes adult faults and the twisted logic that grown-ups use to justify their unreasonable actions.