May 18, 2018:
You'd have to patiently explain things to them. Often many times.
One time he smugly insisted on offering me retirement advice. "You should get a Roth IRA," he repeated, many many times. I told him, "Roth IRAs cap at $90k annual; I'm not eligible." I had to repeat that, or versions of that, a lot. Finally I said with exasperation, "If you make more than $90k you can't have a Roth IRA. I make more than that. A lot more. Four times more." Then he went very quiet, digesting that last nugget.
She was baffled by the concept of air traffic control. We were watching the opening of Close Encounters of the Third Kind. She didn't understand the purpose of the controllers. I told her, "Airplanes aren't allowed to fly arbitrarily anywhere they want. People on the ground monitor them closely by radar, staying in radio communication. They direct the pilots: Turn this much, climb this much, increase your speed this much. This is why planes don't run into each other: these people on the ground are keeping them far enough apart." You'd think that'd be clear enough. It wasn't. She blinked, tilted her head, repeated, "I don't understand what they're doing."
She believed my recording studio was a single large stereo, where I played records on exaggeratedly sophisticated equipment, the way a rich hobbyist would. I tried to show her how it worked, but she was blank.
I thought, maybe there's a language barrier. No. She's simply not very bright.
He probably is. He's too smug, too self-satisfied, too narcissistic, to hear what you say.