Remember the media principle of “if it bleeds it leads,” which means bad news or salacious headlines are designed to grab our attention. When authors are constantly barraged by bad news, it can be demotivating at the very least.
I’m sure sales for your book could be better. I’m with you. Instead, you might consider the number that have sold. If it is only 100 copies, put all 100 people in a room and stand in front of them and discuss the ideas your book presents and how those ideas have changed their lives.
The prophet Jeremiah toiled for 40 years and had only one convert (his secretary Baruch). His words were burned by the King, piece by piece as they were read (Jeremiah 36:20-27). Not once did he see any change in the people of Judah. But his words were not wasted.
Therefore, when any industry news crosses your eyes or ears (closure of a favorite store, a less-than-stellar royalty report, Amazon is taking over the world, etc.), take heart. Books are still selling. Words still matter. Writers are still needed. Oh, and one last thing, God is still sovereign over all things.