There is no reason to say that Gambling is bad for society even it may contribute to being affected nationally. Gambling not only affects the people who are gambling and as it is related to money it affects the members of the family, friends, relatives, and later on the nearest people, and in this way, it affects the whole of society.
Yep, with the right tools and self-control, the risks of things going south can be minimized.
However, you are right - it comes full circle through the gamblers to all people near them.