Ok so you have said that:

If I have an interpretation of American Psycho that is that it is a critique of society... than this means I am only capable of criticizing society when watching a movie.

Well for one, no, that is not personally true of me, and most importantly, that is not even kind of logically valid to assume or infer.

If I read a book and have opinions about it, does that mean I do or do not have similar opinions of similar real world situations,? Does it mean I do or do not incorporate those opinions into other parts of my personality, or job, or activism or lack thereof?

No. Obviously no. To make that leap would be a vast overgeneralization.

Sure, some people have opinions about art and media, but it doesnt affect their actual lives and actions much. Other people have strong convictions that drive much of their lives, and have consistent views on art and media to go with them. Still others may have an obviously hypocritical view of a real world situation, or not even realize the similarity of a real world situation due to ideological blinders. And others are every other possible kind of something else.

You end with literally begging the question, the answer to which was my whole original point:

Dont use overgeneralizations and assumptions to assume you know what a person thinks, when you could just actually ask them what they think.