If that's the case, he's an utter fool. One didn't have to listen to what others were telling them to know about Obama; all one needed to do was listen to Obama himself and have even a cursory knowledge of his past. Don't try to tell me Trump wasn't that sophisticated. He knew damned well what Obama and his minions were all about.
I read Dreams from My Father when Hillary was still the presumptive nominee, but Obama was coming on strong. I can honestly say that nothing that has happened has been a surprise. Horrifying, yes, but not a surprise, given his background.