system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: The Green Lumber Fallacy

I ran into it on Wikipedia, and I can't for the life of me understand it. Halp.
gpt
It’s basically the idea that what looks like important knowledge about something may not be important to doing it well, and what looks unimportant might actually be really important. 

The name comes from a story about a guy who was very successful trading (making investments) in “green lumber”. He was objectively good at it, he makes lots of successful trades over a long period of time. It turns out he thinks that “green lumber” is wood that is literally the color green. It’s actually lumber-speak for “freshly cut” and it’s brown like any other wood. This guy was incredibly ignorant about something as basic as the substance he was actually trading. *But that didn’t matter because it wasn’t important to what he was doing.* 

You do not need to be an expert on everything about a subject to be good at it...you only need to be an expert in those things that matter for how good you are.