Instead of trying to stop these newbies not to go on trading because of their lack of experience and skills, my advice is, let them trade and experience on their own how risky trading is, that way, they will learn trading the hard way. And for sure, the next time they trade, they will prepare for it to avoid further losses.
In reality, no matter how we discourage newbies not to rush in trading, the more they will force themselves to try trading, until they will start trading on their own and realize that there’s no easy trading, everything is actually tough and risky.
Sometimes, even beginners who are new to trading need hands-on experience. So, I personally understand what you mean. We should educate beginners that it's best to start with money they're prepared to lose, and only use a small amount of capital at first. This small amount won't affect their mentality, even if they do suffer losses.
This is actually a good step. Because when beginners fail in their first attempts, they'll immediately understand how challenging trading is, and how much it's not as easy as people portray on social media. Afterward, the beginner will be motivated to learn and prepare more thoroughly. This firsthand experience can sometimes help traders better understand what they need to learn first, and they should also examine the mistakes they make in their first trades.
This idea may seem reckless, but it can actually be effective as a learning experience, provided the beginner only uses very small capital and is prepared to lose. This way, he'll gain immediate trading experience that will help him realize how challenging this field is, and he'll realize that he can't jump right into trading without sufficient insight. This will motivate him to learn more about trading itself.