man - rather, “the man,” namely, the miser (Ecc 6:3-6). For not all men labor for the mouth, that is, for selfish gratification.
appetite - Hebrew, “the soul.” The insatiability of the desire prevents that which is the only end proposed in toils, namely, self-gratification; “the man” thus gets no “good” out of his wealth (Ecc 6:3).