You don't know the exact effects of gambling before you start playing.
You may have heard them before but it is different to hear from others experience than noticing by yourself. This is why more and more people start gambling and getting greedy as they play more. The feeling and the excitement of gambling brings the effects.
We don't really need to experience in order to know, we have other people who are kind enough to share their experience, I think we can learn from them.
Gambling is about mindset. Even though the adverse effects already known or experienced, some people will still do it. Everyone will have their own thoughts about it and only people who can control their emotions during the gambling process who will usually survive.