"Self-improvement", as a concept, has become culturally estranged from becoming a better person —despite the closeness of the two in denotation. Someone could become vegan in order to become a better person, hypothetically, but for the most part, real vegans are people who've already become good people, and that very goodness leaves them no other choice (i.e., other than to become and remain vegans, as a corollary).
