This is an interesting discussion. Well, you're kinda right that a successful trader does not want to spend lots of time on courses or lessons.
However, I know of a successful trader who has a live account, and he's consistently profitable. Since I started following him, his account has minimal drawdown since about 2 years ago and is at equity high so far since then. He sells a monthly subscription with his daily reports and has a course he charges for as well. But he does not spend time on Youtube, Instagram or Twitter, so it doesn't take up his trading time. He doesn't have a family living with him, so I think he does it because trading is a solo activity, and it's nice having a community around. Also, he has a bit of an ego (not in a bad way, but he likes being right and has strong opinions about the market) so having a group of people following him is a form of validation.
It's about Maslow's hierarchy of needs. Once you fulfill your financial security through trading, you probably want to teach others to fulfill a greater need for your ego and self-actualization. Again, why is the mentor I mentioned above charging for his reports and course? I think it's fair if you put in that amount of work and research doing up the daily reports. And from his perspective, why give away the course for free when he put effort into creating it? It's not about the money, but the principle behind it.
There are some successful traders who gives away their material for free. But it's usually in the form of video courses or a PDF that they do not need to update daily.
Of course, there are many fake gurus who make money from selling courses and classes. As always, caveat emptor, let the buyer beware.
So the point I'm trying to make is, if a trader is successful, it's up to them whether to charge or not to charge for their course or material. There are however many fake gurus in this space, so just be very careful who you pay your money to. Do your own due diligence and research.
