Ceng Shiqiang's classic lecture on Chinese studies, why is Feng Shui credible or not?

Feng Shui is really useful, but it is for ordinary people, because ordinary people are unstable and easily changed by the external environment. For a truly wise person, any feng shui is the same, because he will not be changed by the external environment. On the contrary, he can change the outside world with his own mentality, which is why people live in happiness.