My advice - BE CAREFUL
Investment and trading books, articles and videos are made by people who might not actually be winning traders. They make their money by writing "investment materials" and sell it to us, the plebs.
You are very right about this, most of those people writing those books and producing those videos are not really a professional traders, they are just doing it for the sake of money that's why we all having to be careful, that's why in most videos on YouTube, they always talk about the profit they made alone, and they will hardly talk about the losses in their trade just to attract people to their page, because if they are making all those videos to truly educate people, they will be talking about both profit and lose, no matter how professional you are as a trader, you will definitely lose money, you cant be making money always.
All what i will tell newbies that are trying to learn how to trade, can read some of those books or watch some of those videos just to learn the basics of trading, but they shouldn't follow their strategy, they have to learn their strategy on their own, i know even if they are selling those books for the sake of money, they will be able to teach the basics of trading. So as a newbie trying to learn how to trade newly, you have to start with a little amount because you will be losing money during your learning process.