poseer

noun
  1. A person who poses, especially in a manner that is insincere or intended to impress others. noun
    The party was full of poseers trying to outdo each other with their fashion choices.
    He was known as a poseer, always pretending to be more knowledgeable than he actually was.
  2. Someone who adopts a particular attitude or position, often for effect or to deceive. noun
    She called him a poseer because he always acted like he was part of the elite crowd.
    The artist was criticized as a poseer for claiming to support causes he didn't truly believe in.