If you read the whole thing, including the linked information, you’ll see that’s pretty damn good. Better than most native speakers and much, much better than non-natives. But I’m not alone. The results I’ve seen from other guildmembers seem to indicate that they too have pretty extensive vocabularies. Not necessarily as extensive as mine, but definitely noticeably better than most non-natives and on par with native speakers.
Where does this stem from?
I have the added advantage of having worked in the academia, but I believe a major contributor to my vocabulary is my gaming hobby. Many of the words in the survey are terms used in games. Not all, but many.
Now, although vocabulary doesn’t equal intelligence, there is some correlation. If you build something, you are going to be able to do it better, if you have the proper tools. In thinking, concepts are the tools we use. These concepts are then abtracted into words, which work as shortcuts in our thinking (see this post from Saturday).
The more of these shortcuts (or tools) we have, the more efficient our thinking becomes.