Don't do it or don't be so stupid?

In Chinese there is an old saying "若要人不知，除非己莫為".
Meaning "Don't do bad thing if you don't want to get caught".

However, in recent years, there is another saying in Cantonese "若要人不知，唔好太低B".
Meaning "Don't be stupid if you don't want to get caught"

This is a funny example of how Chinese evolved in Hong Kong. It looks like creator of the new saying was trying to play with rhyme, but the outcome does have another meaning that caught plenty Hong Kong people's heats. I do believe the new saying is referred and used more frequently in Hong Kong nowadays.

Sad thing is, the old saying is asking people to be good at heart and not doing bad things, while this evolved one is going the other direction.

So Hong Kong people getting more evil or they just don't care about decency anymore?