Ecclesiastes 4:7-8

7Then I looked again at vanity under the sun [in one of its peculiar forms].

8There was a certain man—without a dependent, having neither a child nor a brother, yet there was no end to all his labor. Indeed, his eyes were not satisfied with riches and he never asked, “For whom do I labor and deprive myself of pleasure?” This too is vanity (a wisp of smoke, self-conceit); yes, it is a painful effort and an unhappy task.