Actually, both gambling and alcohol addiction are very harmful to people, but I don't think anyone would say that alcohol, if consumed normally, will not harm us.
And the bigger thing is that gambling has not yet become such an epidemic that we need to raise awareness by raising banners like this. Rather, I think it can have a bad impact that those who are under age, I am mainly referring to, may become curious about gambling, from which they may also become addicted to gambling even though they are underage.