We're glad that there were gamblers before who took risks and suffered losses. They are now our tool for learning, and yes, because of them, we change. However, this won't make everyone pleased to change their behavior and thinking. Many still live in greed and stupidity. That is why we don't wonder if gamblers have fallen into addiction, committed huge debts, etc…they never realized the situation yet.
What saves us from doing stupid things is to learn from our mistakes. If this makes it difficult, I don't know how gambling ruins our lives.
Some people didn't learn from the mistakes of others, they ignored it until they experienced it and learn from their own experience but the experience sometimes is not usually good. If you learned from the experience of others, it's really good, you won't be too greedy, nor allow yourself to be addicted, or even take the kind of risk that will make you have health issues like some people get depressed after being disappointed by a bet they totally gave all their hope.