The main reason is that Feng Shui involves a lot of negative information. If you accidentally provoke some ghosts, you will be in trouble.
One more thing, no matter what you predict, as long as it is to save people or cross people, there is no limit to merit. For example, you can use your knowledge of the Book of Changes to guide others how to do things and live a better life. In that case, it is a good thing. 、