'Alone' in the Bible

Sometimes a man is all alone with no companion; he also has neither son nor brother. Yet there is no end to all his toil, and his eye is not satisfied with wealth. [He laments,] "For whom am I toiling and depriving {myself} of pleasure?" This also [is] vanity--it is an unhappy business!

Look! This alone I found: God made mankind upright, but they have devised many schemes."