I need answers

If you ask any man in America, or any man in business in England, what it is that most interferes with his enjoyment of existence, he will say: "The struggle for life. He will say this in all sincerity; he will believe it. In a Certain sense it is true; yet in another, and that a very important sense, it is profoundly false. The struggle for life is a thing which does, of course, occur. It may occur to any of us if we are unfortunate. It occurred, for example, to Conrad's hero Falk, who found himself on a derelict ship, one of the two men among the crew who were possessed of fire-arms, with nothing to eat but the other men, when the two men had finished the meals upon which they could agree, a true struggle for life began. Falk won, but was ever after a vegetarian.
Now that is not what the businessman means when he speaks of the 'struggle for life'. It is an inaccurate phrase which he has picked up in order to give dignity to something essentially trivial. Ask him how many men he has known in his class of life who has died of hunger. Ask him what happened to his friends after they had been ruined. Everybody knows that a businessman who has been ruined is better off so far as material comforts are concerned than a man who has never been rich enough to have the chance of being ruined. What people mean, therefore, by the struggle for life is really the struggle for success. What people fear when they engage in the struggle is not that they will fail to get their breakfast next morning but that they will fail to outshine their neighbor.
1. Why do American businessmen presumably feel unhappy?
2. How do they misinterpret struggle for life?
3. What does struggle for life actually mean in the paragraph?
4. What is the difference between struggle for life and struggle for success?
5. Have you got a personal definition of success and happiness? (Not more than 5 to 6 sentences)