What is the significance of banning gambling?

Gambling is a zero-sum game and does not produce any social value. For example, a mahjong, four people are playing, no matter how many times they play, the total amount of gambling money owned by the four people is always the same. It's just that wealth has been transferred between four people.

The practical significance of banning gambling is to keep people away from meaningless activities and put more energy and time into actual production to create GDP.