Gambling addiction is really a silent killer, what it harms mostly is your mental health and finances just as you stated earlier. A gambling addict will always be in a mood influenced by the outcome of his bet for the day. They could either be happy or sad depending on if they won or lost in their gambling activities.
Addiction as a whole is dangerous, it needs an expert intervention so yeah, I'll agree with you that gambling is a silent killer that harms ones mental health.
Don't overlook the damage it causes in relationships. Many once lovely families have been destroyed because of gambling addiction. There was a story on this forum about a young man who gambled away all the money they had saved for their marriage. My neighbor, who is suffering from a gambling disorder, once used his children's school fees to gamble. This action nearly ended their marriage. It took the intervention of family and friends before they were able to reconcile.
There are currently many families in which one member suffers from a gambling addiction and the other is codependent, and both are struggling to cope. I'm glad when they recover with the help of specialists who help them fight and overcome it, but I think a more negative scenario occurs, in which families break up because one spouse simply can't give up gaming because it takes precedence over the other. It's better to look at these negative experiences and understand what awaits us as gamers, avoid this path, and maintain complete control over our gaming.