because people judge gamblers to be stupid people, why they risk their money to gamble, which sometimes can make all the money lost, and people think why they do not use money for investment or other business. so for good, gambling will be called a negative thing.
People dont judge gamblers as stupid instead of they think about them that they are stupid because they are promoting something which is dangerous for their lives and also for the lives of the people who are attached to them. Gambling is a negative thing when it is being played for fun but it playing as a source of fun is something which cant be opposed.