Mr Richards has worked in a small seaside town for about ten years and he and his wife have a comfortable house near the sea. During the winter they would be quite happy, but every summer a lot of their relatives used to spend holiday in their house, and it was much cheaper than staying in hotel. Finally one day in June Mr Richards complained to a clever friend of his who lived in the same place. "One of my wife's cousins is going to bring her husband and children and spend ten days with us next month again. How have you prevented all your relatives from coming to live with you in summer？" "Oh," the friend answered, "that is not difficult. I just borrow money from all the rich ones, and lend it to all the poor ones. After that, they seldom come again." Hearing this Mr Richards smiled.The relatives preferred to stay in Mr Richards's house because（）.