Unless every single one of those books is a word for word restatement of the wikipedia page, there is information about sociopathy which is known, and yet I do not know it.

To be fair, I've read books hundreds of pages long which contained less information than a reasonably complete Wikipedia article. There's almost no limit to how much you can write about a limited data set if you're at all good at storytelling. This is truer than usual for pop science, and especially true for pop psychology.

That being said, and clusterfuck though it is, ASPD and related disorders are probably the most intensively studied cluster in personality-space -- the study of "criminal insanity" (from which there's a more or less direct line to the modern understanding of ASPD) considerably predates Freud. The DSM criteria are purely descriptive and probably don't describe a natural kind with any great precision, but volume of data is not going to be a problem here; can't say the same for interpretation, though.