Everyone should understand that gambling is good only in moderation, excessive enthusiasm for gambling leads to disastrous consequences. If you want to teach someone how bad gambling can lead to - show him examples of players who have lost everything in life because of the game.
If you want to tell anyone about the gambling, then you should tell do justice and tell both sides of the gambling, Good and Bad, advantages and disadvantages. We should tell both aspects and leave it to the person to decide whether gambling is good or bad for him.
We should not force anyone to join gambling.