、。
Some people take a bath every day, and some don't.
Literal
Every-day bath [into-に] enter people [also-も] exist-[conditional-ば], not-so people [also-も] exist.
~もいれば~もいる is a balanced contrast structure: 'there are those who X, and there are those who Y.' The ば conditional connects the two halves symmetrically. そうでない ('not so') elegantly substitutes for the entire preceding predicate, avoiding repetition.