The phrase "from frugality to extravagance, from extravagance to frugality is difficult" comes from "Tongzhi Jianjian", which means that our living habits are from frugality to extravagance and from extravagance to frugality.

This sentence has been passed down to this day and has become the motto of educating everyone to abide by the fine tradition of thrift and housekeeping. At the same time, this sentence also reflects a consumption characteristic of people, that is, when people form a consumption habit, it is difficult to change and reverse it. When people's income increases, they easily become extravagant, but when people's income decreases, they need to lower their consumption standards, but it is difficult to adapt. From an economic point of view, this consumption habit is called "ratchet effect".

"Ratchet effect" was put forward by Duesenberry, a famous American economist. His main point is that "people's consumption habits are irreversible after they are formed, and it is easy to adjust upwards, but difficult to adjust downwards." It is most obvious in a short time, and the habitual effect of consumption is great. After they develop luxury consumption habits, it is difficult to adjust their consumption habits immediately with the decrease of income level. " For example, if someone is used to living in a luxurious big house and then moving to a small house, it will be difficult for him to adapt; Some people are used to the life of big fish and big meat, and it will be hard for him to accept if he is allowed to return to that simple life.

The ratchet effect is also a manifestation of human nature. People are born with desires, and proper desires are conducive to promoting people's progress. However, everything must be measured, and excessive luxury will have a bad social impact, which is not desirable.

Phenomenon 2 of life economics:

Many girls feel that they can't be wronged and set their "opportunity cost" too high. They always feel that they can find someone who is better than themselves in all aspects. I have to find 5 out of 3, and 7 out of 5, but excellent people are often in the minority. I don't want to work hard, but I want to find a high-quality boy. If I can't find him, I don't want to be with people with similar or worse conditions and reduce my quality of life. That's the only way! Many boys are single more because their conditions are not very good and they don't want to wronged themselves. They think that their continuous efforts will increase their "opportunity cost" and find more satisfactory ones. In this way, there will be more single men and women.

There is also an "opportunity cost" principle in economics. It refers to the opportunity cost of this decision, which is the highest value among the abandoned options in the face of multi-scheme alternative decision. Simply put, when we give up something in order to get something else, "opportunity cost" refers to the biggest loss after making a choice.