I think that most things can be taught, and I would include currency trading among them - I myself went on a course, as I was a blank canvas coming from an unrelated industry it worked for me. My trading style is basically S&R mixed with PA, this is something that can be learned for free from the various internet resources available. Some will prefer the contextualized scenario of structured learning, able to ask questions in context, with a consistent set of teaching, development etc., as well as other class members at around the same experience level. Others will prefer to self teach. Both work well, as long as the individual concerned is a good fit, both for currency trading and for the particular learning style. Similarly, coaching/mentoring can work well for some, not so well for others. There are many variables, not least the aptitude of the student and the quality of the coach, both as a coach and as a trader. Unfortunately, much of this is not apparent from the outset, but will only be learned through experience, so there will always be unhappy tales. Most things boil down to an element of trial and error!
What is certainly true is that no coach can replace the need for hard work. I had a coach for over a year, it brought me on enormously, gave me valuable insights, massively improved my trading and accelerated my learning a great deal... but I still had to work very hard at my trading.
Personally, I trade simply S&R/PA, I found a coach very helpful, but the only essential element is hard work and the consistent, mechanical execution of an effective strategy, imho.
ST