Your friends apparently believe that a serial rapist, swindler, convicted felon, incompetent "businessman" is an acceptable choice for the Office of President of the United States. They apparently believe that it's OK for a departing President to steal highly classified secret military information.
Or perhaps these friends just don't "believe" what we all know to be true about Donald Trump. Perhaps they're just fixated on their own finances, their own portfolios, their own families, and generally don't think much (or at all) about their role in a community, their responsibility to that community.
Maybe some of them are racists, and are OK with Stephen Miller and ethnic cleansing.
Look, I can understand people supporting George (HW or W) Bush, or John McCain, or Mitt Romney, or Paul Ryan...or (I thought I would never say this!) Richard Nixon. But Trump?
Trump lies about everything. Trump is deliberately cruel. Trump steals from everybody he deals with, if he can get away with it (stiffs contractors, swindles customers). Trump cares for nothing, and nobody, but himself. (OK, I realize that some might just call that "libertarianism.") Trump has driven almost every business he's attempted into the ground; he's not a competent manager.
Trump tells people what they want to hear, and he's a good conman, so lots of people believe him. He's going to cut energy prices in half, in one year! (So he promises; he has no clue, of course.) He's going to bring down the cost of beef! (I originally typed that as "beer" - that would work, too!)
You say your "Republican friends" support Trump. I shudder to think that you're talking about professional associates - people who are educated, and theoretically trained to be able to distinguish between fact and fiction.