What is the academic argument against Sci-Hub? I know that some consider certain activities of Sci-hub to violate the law in some jurisdictions. Many of the previous questions and opinions related to Sci-hub have focused on these legal aspects (and they are certainly important to consider). 

However, I am wondering what are the main harms or downsides associated with the existence of Sci-hub and similar services from the perspective of academics, researchers, and students. I am asking because this topic is relatively new to me, and I would like to better understand the main cons of Sci-hub as perceived by fellow academics (as opposed to publishers or lawyers).
What is the academic argument against Sci-Hub?


There are none.  The arguments against sci-hub are legal or economic.  Copyright is a legal right, not a moral or intellectual right.  

You could argue that repositories like ArXiv or open access journals are better than sci-hub because they are more reliable.  But that is not an argument against sci-hub.