I'm not sure if vocabulary size matters once you reach around 25,000 words. The words I didn't know were in part because I've never had any need to know them; if I had run into any of them while reading anything written in the past 80 years, I'd be angry at the author for showing off.
When I was young, I thought that if I wanted to be a writer I should have a huge vocabulary... but now, when choosing words/synonyms I dismiss most options because they're much too obscure.