some say the difference between the poison and the medicine is the dosage
supposing someone can control themselves and gambling is just something they do for entertainment, not an addictive behavior, it should be fine
but I'd agree with you that most of the times it's not like that.
Perhaps this is a subjective impression, since we do not know all the statistics, and the news is mostly negative. For example, we can easily see a news report about how someone lost everything in gambling and killed himself, but we never read the news about how "John Smith visited the casino today, drank a couple of glasses of beer and after a couple of card sessions went home satisfied".