Trading is very very complex, if not carefully followed with caution it may lead to An uncontrollable addiction that sometimes have consequences like that of Gambling.
From his story it seems like he traded without adequate knowledge, self control and with Greed.
I can't see why a content creator that has amassed a good amount of money would still trade like a greedy trader.
Well nevertheless if it is really true, then I hope he learnt some lessons.
Learning trading is about 80% from experience, infact trading is the definition of experience is the best teacher, that's why is good to back test and an practice in a demo account so you dont need to get those experience from your real money.
You are somewhat right. It is possible to get knowledge from a demo account, but it is not possible to get 80% knowledge. There is only one difference between a demo account and a real market. A demo account does not require money. A real account requires money. But the market is always the same.
Now the main thing is that most of the users are not emotional while using a demo account. They are ready to take any trade without thinking much. They do not have any thoughts in their mind that they will lose or win. They just keep trading according to the instructions given by their mentor.
But, when they do real trading, they are most afraid of losing money. They cannot get the thought of losing out of their mind. They feel pressure in every trade. Due to pressure, they make small mistakes again and again.
This is one of the reasons why a trader loses money again and again.