My brother is 76 years old and still acts like this. For Thanksgiving my wife and I drove to CA to visit with his family and some other family members and guess what? He started numerous arguments while I was there. Socially inept is how I see him. He argues either side of a discussion. Or just starts arguments where none existed. Fortunately, I can just tell him to stop and he knows well enough to do so. But it is tough dealing with him at times because he is my brother.
My former sister (I disavowed her when she failed to care for our mother when she had multiple strokes) believes her opinion to be the Gospel, and all opposing viewpoints are not to be believed -- in spite of direct and overwhelming evidence.
She once asked me to take her cat to the groomers for her as a favor. The groomer was about an hour's drive from where she and our mother lived.
I asked at the time how much it cost, and she said she always paid $35. I asked if that included the tip, and she looked surprised. "I never tip her." That's when we got into an argument over the services industries, how the woman held her cat's life and wellbeing in her hands, and if she did a good job, she should get a tip.
My sister came up with:
"I need that $5 more than she does".
"If she wanted $40, she should make that the price."
"The whole time I've used her, she never once asked for a tip."
and, of course, my favorite (after I had pretty much convinced her she was wrong) ==> "Well, you don't know
every thing!" Can't argue with that, huh?
So, I took the cat, did some shopping in the area rather than spend 4 hours driving, and picked up the cat. The cat's either a Persian or Maine Coon mixed with super thick fur. The cat looked like a giant fur ball when I dropped her off. When she was ready, she looked fantastic -- close-cropped fur and as even as any stylist could do.
When I handed her 2 x $20s, she started fishing for my change. When I said, "Don't bother. Keep the rest," she looked like I was speaking Martian! She knew I was my sister's brother, and fully expected me to not tip just like her. It obviously made her day based on the smiles and thank you's.
That night, my sister asked how much I paid, and I told her $40. I also said the tip was on me if she's that set against paying. She remarked what a great job the groomer did this time, and I think it finally hit her how good service like that should be rewarded with a little more than the going rate.
She wrote me a check for the $40.
All that drama and head banging over $5, and in the end, she hopefully learned something. BTW, she was 46 at the time.

She's always been this way. She knows what she knows, and it's like pulling teeth to get her to turn loose of any opinion that she truly thinks is correct no matter what the facts say.
We haven't had much of a relationship since she ask if my daughter could spend the night once -- and gave her a lecture on the evils of alcohol, and that her parents (us) should stop drinking. My daughter was 4 or 5 then.
