The word for them is snobs. They would probably prefer to be called aficionados or experts. But no, the word for them is still snobs.
They are those people who look down on you for your lack of knowledge about Beethoven and Debussy. Who judge you because you don't know the difference between pointillism and impressionism. Who look at your feeble attempts at a novel and laugh out loud.
Every field has them, and in the creative arts, the opportunities for snobbishness increase exponentially. Because creativity is often not always a skill taught but sometimes a talent acquired. Some people are just born with it, and learning all of the extras is the easy part.
On top of that, there is the specialized language. When you as a classical music person a question, they will answer with words like adagio, diminuendo, and other Italian words that you have no idea what they mean when they could have just said "slow" and you would've understood what they've said.
These elite use the terms of their field to differentiate who is in the know and who isn't. It's a pretty good litmus test. A few can pass through the first few uses, but once you keep going through your laundry list of words, pretty soon the intruder will stumble and you'll know them for who they really are: a wannabe.