'Gain' in the Bible

So I thought to myself, "The fate of the fool will happen even to me! Then what did I gain by becoming so excessively wise?" So I lamented to myself, "The benefits of wisdom are ultimately meaningless!"

What benefit can a worker gain from his toil?

When someone's prosperity increases, those who consume it also increase; so what does its owner gain, except that he gets to see it with his eyes?

This is another misfortune: Just as he came, so will he go. What did he gain from toiling for the wind?

So what advantage does a wise man have over a fool? And what advantage does a pauper gain by knowing how to survive?

When I tried to gain wisdom and to observe the activity on earth -- even though it prevents anyone from sleeping day or night --