I disagree. People just don't take drugs or alcohol to destroy their lives. Many of them are just into depression, after all, in all truth, life actually sucks. It's not a bed of roses for many. Drugs or such are a way to physically suppress the mental agony, not that I'm recommending it.
However, gambling addiction is worse than drug addiction. Drug addiction atleast has a benefit that it reduces depression, but gambling takes away from you, your health, your money, brings depression.
It is already a different matter because drugs and alcohol are very influential on health, body, and mind, need to be distinguished between habits and addictions. The consequences of gambling are not more severe because it is more psychological with material and objective thoughts, this can still be cured naturally, especially when they realize they have nothing to facilitate their gambling addiction anymore. Some of them will fall, but most will succeed in recovery, all they do in a conscious state even though sometimes without control.
Both of them will affect our life the same. Being in addiction will consider it also as habitual actions that a person will do. They are totally out of control and ruining their lives and their family. Drugs and gambling addiction will give nothing to us. Yes, they are of different sources but the result will be the same and lead to us mental disorder of not given a cure. But to think which one is the worst, it probably drugs addiction...it won't give anything in return unlike what will happen to gambling which we could still have a chance to win and make some money.