Gambling is particularly dangerous because you can get financial ruin extremely fast, compared to other addictions.
I don't think gambling addiction is the most dangerous compared to other addictions, as you said gambling addiction will make ruin your financial, that's all. Actually drugs addiction is way more dangerous than gambling addiction since it will ruin your financial and your health condition. If you lost all your money but you still have a good health and body, you can get a job. But when you don't have any money and you're sick due to drugs, it's almost difficult to get a job to make you survive.
To a certain extend yeah, but you have to remember that sometimes gamblers who are addicted can do things beyond our comprehension, the worst is stealing money which is worst because you can go to jail for doing that. So there is no lesser evil here, both have a negative impact not just to the individual but the person around him/here. Love ones that can ruin their lives.
When someone is addicted in gambling they sometimes treated as abnormal. I know a lot about gamblers where they commit various crimes while managing gambling money. I have heard that they don't even dare to commit murder. There are many such addicted gamblers in the world who even kill for money. Generally those who don't have financial support they do such type of crime but if someone is from a rich family, it is different. Addicted gamblers are always socially scorned.