There's so much bad history about gambling, and because many were very religious back then, that's why there are not so many advertisements.
But today? I see billboards of gambling ads, and most of them are regulated by the government. Maybe not in your country, but it is with us. Then, there's social media. I believe the marketing attack in today's era is not on the billboards anymore, it's social media where most people spend their time, and they can easily gamble by just pressing the link or installing the application.
They actually don't need those physical ads anymore. All they need is a good commercial or a popular artist to use in their ads. Make it look more appealing and reputable at the same time.
Gambling has become very destructive to a lot of people and it has become very evident to a lot of in the society. This is the reason why the government has stepped in to ensure that this dangerous habit is being eliminated from peoples minds. But gambling should not be that only thing that needs to be emphasized on because even drinking,smoking and all that has the potential of causing a lot of damage