It's true we will never know until trying it, after all based on my own experience, Udemy is good enough for beginners and also the price offered is cheap with the knowledge that we will get. Another positive thing about Udemy is that there are many positive reviews about Udemy, so at that time I did not hesitate to try trading courses on Udemy. But that doesn't mean Udemy is the best and doesn't have flaws, there are still platforms that are better than Udemy, but the price offered is very expensive.
I think this site is great enough since I've been hearing lots of these in the past but about the prices offered I think they can differ depending on the author of those courses. High quality courses doesn't usually come cheap but they can be worth it compared to those cheap ones where you cant become really good after finishing it. Udemy has a positive review but I think there are still individual reviews depending on the course.
We should look at them too before we purchase so that we know what to expect and we can minimize our chances to get scammed by picking a bad quality course. Social media is a different thing and cant be compared to sites like Udemy.