Its easy to say that because you don’t experience to gamble yet, but those who are already involve on that situation may feel the different. Basically gambling is ok if your purpose is just to have fun but since gambling gives so much pleasure that turns to greed, then that’s the time gambling is bad.
Yes ask addicted gamblers how they feel and what all issues they are facing in real life. it is easy to say but in real time it's not easy you have to struggle a lot to overcome all your issues. maybe he was not experienced worst thing in gambling that is why he is telling like this. once you show greediness in gambling later on you will face only negative effects.