Making content copying-resistant

Hi, I am looking for a way to protect the content that I include in my courses. The goal is that no text is available for copying. As I understand, it is nearly impossible to prevent the text from being copied with html-editor. So I tried uploading a pdf secured with a password (on my local machine no reader or Acrobat could copy a single letter without gaining access with a password). It was readable but neither printable nor copyable. Nevertheless when shown in a slide with the default viewer on the lesson page, the pdf was completely copyable. Interestigly, when I downloaded the embedded file I was no longer able to copy anything from it. Again! So how do I come around this issue? Is there a way to protect the information we as educators are selling?