If a young professor had to teach an introductory course (say Physics, Calculus, Chemistry, CS) the first time and didn't have a curriculum, notes, problem sets, tests and stuff available they'd have to work very hard.
If you inherited all that stuff and then spent 30 years teaching the class you find it very easy.
I have an online antagonist that I really want to screw into the ground. I have been studying a subject that person talks about for a little more than six months. I think I am at the 25% mark of being an "expert" on that subject.
Already I can write a few sentences that destroy one of those person's blog post maybe 20% of the time. If I get to the point where I am 80% successful at that I'm going to feel like I've won at "debating" if not actually practicing the subject... And those are entirely different things.
Discussing a subject like that pedagogically is a lot like developing a comedy routine or other performance, it takes getting your emotions and motivations in the right place, practicing over and over to not get hung up (or have your listener get hung up) over details, etc.