I don't believe that Gambling helps Bitcoin in anyway , If someone joins the bitcoin community just for gambling then sooner or later he will lose everything and probably leave the community.
People should see Bitcoin from another perspective and not only as a gambling or a Darknet tool.
But it is also a way for people to be encourage. Some cant stop gambling and it is not affordable for others when they do outside casino. In bitcoin they can use a little money to play some. It will depend on them if they want to leave after losing. But for me it is also good for bitcoin.