Seems to me that "good" trading is not even possible for most people. Competant, is another question. Sure most people who understand tech, markets and are willing to learn, and work hard reading, I imagine you could become competant if you wanted, but "good" is another matter.
I suspect, "good" quality traders, meaning those who regularly earn gains, not lose their shirts, in either/both bull and bear markets, these people probably need to be a certain breed.
I suspect trading is like sports or any other skill.
Seems like your guest disagrees with me, but that is my thoughts on the matter. He makes it sound pretty easy...