Alcohol and gambling can be very addictive for people who lack self control, that is why a lot of negativity is attributed to both. In my country alcohol and gambling adverts are in strategic locations for many people to see them, they're both also online and on TV. If I want to compare between gambling and alcohol the one that is more harmful and it's addiction can be very damaging than the other I'd say that it's alcohol. Gambling addiction will make you to be broke and always emotional but alcohol addiction will mass with your mind, when you're under it's influence, it takes control of your senses. Alcohol addiction can cause many health challanges which gambling addiction cannot cause.
From my point of view, its harder to get addiction to alcohol, when gambling makes people addicted much easier. The gap between "I can not see my day without alcohol" and "one more drink and I will feel sick" is huge. While gap between playing once or rarely and becoming addicted gambler is only one really big win away. Or gambling can make you broke in a second, while it takes months or years for alcohol to mess persons mind.