Maybe if they want to get that from their thick skull, they need to go do research on finding the number of people who could come out openly to say gambling has made them extremely wealthy in a short period of time. I can bet my last satoshi, that just very few would come out to say so and that leaves the larger percentage in losses.
The best practice is to know that you are not up for any get rich system in gambling and if you cannot deal with that and just simply focus on enjoying your game while gambling with what you can afford to lose, then, it is better not to even be gambling at all.
And once it is mentioned that gambling is a zero sum game, the person who got rich from gambling will be overwhelmed by the amount of people that had to lose money and even destroy their lives, just to have it possible to win that amount of money. This will bring guilt to the winners. Oh well, they still deserve it though since they got lucky.
There actually isn't not much point in becoming rich from gambling if you do not have any background in finance. Why? Because you would have so much money and have no plan on where to spend them. This leaves you in a scenario where you just spend your money just to spend your money (i.e. buying whatever things that came remotely as a "need"). It's the same reason why there's no point in becoming famous on Instagram. Since you're just a regular individual, once you indeed become famous on Instagram after posting half-naked pictures, you're not going to know what to do with the fame or how to even handle it. The fame will just be wasted and fade away in no time.
Sudden increase of money will easily go to waste. The ones who are able to stay rich are the ones who did the effort to build the foundation bricks from bricks. They know what's up and they know the whole process. They know how they got to that financial state and so they are able to maintain it. The opposite is what happens to those who hit the jackpot in gambling. They got rich and have no knowledge how to maintain the wealth. They end up having a grand lifestyle and lose their money in maintaining that kind of lifestyle. And yes, there's financial advisors but sometimes they are the ones who would rip you off.