This is just my own perspective, I can’t really be sure about the others.

First of all, a bit about me.
I’m mainly a Forex Trader, I started in 2007 and turned a full time trader in 2013.
I am not super rich, but I can live a good life trading Forex. Money is not the first motivation for me, freedom is.

I wrote a similar answer on Quora almost one year ago, I was in Starbucks in London in that occasion:

I answered another similar question about a month ago, I was writing from my cell phone in Malta:

I’m answering this question today, I’m in Cambridge and writing from a very quiet place where I can also check the markets and adjust my trades.

I’ll go to Germany in 2 weeks and to Italy in 2 months.
Although I understand that may not sound appealing like having $10 million in your bank account, it is exactly what I was looking for.

About courses
I apply the same principle that I apply for my investments: diversification.
I won’t get any pension as a Trader and it is good to have a second source of income that I can just forward to my savings account every month.
I don’t do anything special, I don’t introduce myself as a new guru of Finance and sell my courses for $500. I always give coupons on my websites to enroll for less than $15. I never ask questions after a refund request. I do it for money of course, but I also do it because I want to leave something to people. I’m not really interested in “stealing” your $10, I put 100% in my courses and I always try to improve, but if you don’t like them, I think it is fair that you get your money back.

I’m not lying, it is another business for me; but I consider appreciation of people more important than money. I really appreciate when people take the course and then send me messages like “thanks, now I have a better understanding of the Forex market” or “I have just made $20 with my first trade”. The moment I realize that my courses are not giving any value and are not helping traders at all, I will stop making them and consider the idea that maybe I’m not a good instructor.
This is the reason why I offer my courses for $10 and I also give the chance to get a refund within 30 days, without asking any question.
Courses are not my main source of income. $100 or $10, it doesn’t make a huge difference to me, but I’m aware that it can make a huge difference for other people.

Some people look for me on Udemy and see my course at $199. I’m not interested in selling my course at $199 and I’m the first person to say “get a refund and enroll for $10 with my coupon”. If you ever wanted to have a look at them, go through the coupons on my website: Education - Quora Forex Questions

Also, you may find this other answer on Quora very useful: Federico Sellitti's answer to If you have enough money, can you pay a trading firm/traders for training? If yes, how do you get not scammed or useless training.