All of these bad things can be found in people without any addictions, so I wouldn't say that gambling is the root of all evil. Gambling, like anything, in moderation is a perfectly fun and normal form of entertainment. It's when people take it to the extremes and don't accept that the games are designed for you to lose in the long run. Every time you play you should expect to lose every penny and be content with that, sometimes you get rewarded with the odd bonus but most sessions will be losers. Don't blame the activity, blame the people who let it take a grip of them or who expected it to solve all their problems by taking shortcuts.
You're right, as they say, excess of anything can be dangerous for a person even if it's something that is generally considered good but if it's done without limits, it can cause issues. Take food as an example, we eat food for nutrition, and we can't stay alive without it, but if we eat excess food, that can cause problems for us because we can get stomach pain and all sorts of illnesses that are caused by consuming an excessive amount of food.
When it comes to gambling, we already know that it has the possibility of wrecking us because there are only two outcomes in gambling, you either win or lose, and since the odds are usually stacked against you as the gambler, you should expect that to happen every time you gamble.
People who miscalculate things and gamble excessively with high hopes tend to face negative consequences for that.