It is dreadfully difficult for the fish to see the ocean in which they swim. That is one of the strengths of any hegemonic system. It is difficult for those living within it to realize that they are, indeed, living "within" a construct when so much of what they see seems natural, right and normal.
One of best ways to demonstrate hegemony induced blindness is to read a book one first read several decades ago. [I would suggest watching a television show or a movie but changes in production value can make it difficult to see past the technological changes to issues of social construction.] One finds upon rereading the book that apparently an evil genie crept into the text during the intervening years to change everything from language to plot details to aspects of characterization. "How could I have missed that!" one cries.
One missed it the first time for the same reason that fish do not notice the water--because it was such an automatic and unquestioned part of the universe in which one lived that it barely impinged on one's consciousness. One missed it because the reader and the author shared the same prejudices, understandings and stereotypes.
And as you put down the book or come to the last frame of the movie perhaps you should take a moment to wonder about all of the other things one had taken for granted or not noticed.