This is the central idea of the passage. So the author would most like agree with this sentence.
Starting a paragraph with tea is just a way to introduce to audience with author's opinion and to make the passage story like and engaging. With this start author's opinion becomes more relevant. The guest's expression "Wow! Even the mugs are twice the size we have back home," triggers author's realization that he has many extra things in his life. At first it starts with overstocked clothes in his walk-in closet. Then he also realizes that he like many of his peers has become wasteful. So a realization of being wasteful and its regret are the main ideas with which author would most likely agree.
