Human nature generally cannot withstand any tests.
In the past, the Cuojin Sect was considered a semi-open harmless organization. They usually neither killed nor set fires, with their greatest goal being Fulong Court.
In other words, they tricked former courtiers into spending money on Feng Shui.
Doing Feng Shui is better than doing other things. The group of former courtiers was still quite large and had a good amount of spare money. If you don't let them study Feng Shui at home, when they have nothing to do, they might cause some other troubles.
Of course, this doesn't exclude the presence of certain bad apples, such as Leng Nian.
The original philosophy of the Cuojin Sect was to disguise and avoid disasters, live low-profile, and stay clear of karmic consequences. If you indulge in Feng Shui while creating problems, and get entangled in the mortal realm, you will inevitably have a bad end.