My favorite is when people get picky about cabling for digital transfer. The ones and zeroes either get there or they don't, nothing in-between. They work or they don't.

Around the time when HDMI was released my friend bought some "super-high-end "cable that cost over 200$, since he wanted the "best possible performance " out of his system. I tried to explain that the cheapest cables would give the exact same results if they're not faulty from the start. We had a loud argument about this, even though the guy is a goddamn tech PhD. He just could not admit he got scammed and tried to give me a lecture about "how the gold plated connectors make all the difference".